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Age_Word_Problems/323329: Ann's age is seven-tenths of Bill's age. In 4 years Ann's age will be eight-elevenths of Bill's age. How old is Bill now?
I am having a difficult time with setting up the equation due to the fractions. Any and all help will be appreciated. Thank you.
1 solutions

Answer 231438 by ankor@dixie-net.com(15649) About Me  on 2010-07-18 10:42:20 (Show Source):
You can put this solution on YOUR website!
Let a = Ann's present age
Let b = Bill's present age
:
Write an equation for each statement:
:
"Ann's age is seven-tenths of Bill's age."
a = 7%2F10b
or
a = .7b
:
"In 4 years Ann's age will be eight-elevenths of Bill's age."
a + 4 = 8%2F11(b + 4)
Multiply both sides by 11
11(a+4) = 8(b + 4)
11a + 44 = 8b + 32
11a = 8b + 32 - 44
11a = 8b - 12
Replace a with .7b
11(.7b) = 8b -12
7.7b = 8b - 12
12 = 8b - 7.7b
12 = .3b
b = 12%2F.3
b = 40 is Bills age
;
:
Find a
a = .7(40)
a = 28 is Anns age
check solution in the statement:
"In 4 years Ann's age will be eight-elevenths of Bill's age."
28 + 4 = 8%2F11(40+4)
32 = 8%2F11*44
32 = 32


Miscellaneous_Word_Problems/323221: In Feb 2006 in the Valley of the Kings in Egypt, a team of archaeologists uncovered the first tomb since King Tut's tomb was found in 1922. The tomb contained five wooden sarcophagi that contained mummies. The archaeologists believed that the mummies are from the 18th Dynasty, about 3300 to 3500 years ago. Determine the amount of carbon-14 that the mummies have lost. (Recall the half-life of carbon-14 is 5750 years.)
1 solutions

Answer 231411 by ankor@dixie-net.com(15649) About Me  on 2010-07-17 21:46:42 (Show Source):
You can put this solution on YOUR website!
In Feb 2006 in the Valley of the Kings in Egypt, a team of archaeologists
uncovered the first tomb since King Tut's tomb was found in 1922.
The tomb contained five wooden sarcophagi that contained mummies.
The archaeologists believed that the mummies are from the 18th Dynasty, about 3300 to 3500 years ago.
Determine the amount of carbon-14 that the mummies have lost.
(Recall the half-life of carbon-14 is 5750 years.)
:
The carbon 14, formula: A = Ao*2^(-t/5750)
where
A = amt after t yrs (We will use per cent)
Ao = initial amt (let it = 1)
t = time in yrs
:
A = 1*2^(-3400/5750)
A = 2^-.5913
A = .6637 or 66.37% remain
therefore
100 - 66.37 = 33.63% has been lost


Miscellaneous_Word_Problems/323282: A large pump can fill a 10,000 gallon tank 5 hours faster than a small pump. The large pump outputs water 100 gallons per hour faster than the small pump. Find the number of gallons pumped in 1 hour by each pump.
1 solutions

Answer 231410 by ankor@dixie-net.com(15649) About Me  on 2010-07-17 21:23:38 (Show Source):
You can put this solution on YOUR website!
A large pump can fill a 10,000 gallon tank 5 hours faster than a small pump.
The large pump outputs water 100 gallons per hour faster than the small pump.
Find the number of gallons pumped in 1 hour by each pump.
:
Let x = gal/hr of the smaller pump
(x+100) = gal/hr of the larger pump
:
small pump time - large pump time = 5 hrs
10000%2Fx - 10000%2F%28x%2B100%29 = 5
multiply by x(x+100), results
10000(x+100) - 10000x = 5x(x+100)
:
10000x + 1000000 - 10000x = 5x^2 + 500x
A quadratic equation
0 = 5x^2 + 500x - 1000000
Simplify, divide by 5
x^2 + 100x - 200000 = 0
Factors
(x + 500)(x - 400) = 0
x = 400 gal/hr, the rate of the small pump
and
400 + 100 = 500 gal/hr, the rate of the large pump
:
:
Check solution, find the time of each pump
10000/400 = 25 hrs
10000/500 = 20 hrs
---------------------
difference: 5 hrs


Word_Problems_With_Coins/323171: A group of twenty-five coins, whose total value is $2.75, is composed of nickels, dimes, and quarters. If the nickels were dimes, the dimes were quarters, and the quarters were nickels, the total would be $3.75. How many quarters are there in the collection?

1 solutions

Answer 231409 by ankor@dixie-net.com(15649) About Me  on 2010-07-17 20:57:16 (Show Source):
You can put this solution on YOUR website!
A group of twenty-five coins, whose total value is $2.75, is composed of
nickels, dimes, and quarters. If the nickels were dimes, the dimes were
quarters, and the quarters were nickels, the total would be $3.75.
How many quarters are there in the collection?
:
Write an equation for each statement:
A group of twenty-five coins,
n + d + q = 25
:
whose total value is $2.75,
we can use cents here
5n + 10d + 25q = 275
:
If the nickels were dimes, the dimes were quarters, and the quarters were nickels, the total would be $3.75.
10n + 25d + 5q = 375
:
Multiply the 1st equation by 5, subtract from 2nd equation
5n + 10d + 25q = 275
5n + 5d + 5q = 125
---------------------subtraction eliminates n
5d + 20q = 150
:
multiply the 1st equation by 10, subtract from the 3rd equation
10n + 25d + 5q = 375
10n + 10d + 10q =250
-------------------------- subtraction eliminates n
15d - 5q = 125
:
Multiply 5d + 20q = 150 by 3, subtract the above equation
15d + 60q =450
15d - 5q = 125
------------------- subtraction eliminates d, find q
65q = 325
q = 325%2F65
q = 5 quarters
:
:
To check solution, find d
5d + 20q = 150
replace q with 5
5d + 20(5) = 150
5d = 150 - 100
d = 50%2F5
d = 10
then
n = 10 also (total coins is 25)
:
Check in the 2nd equation
5(10) + 10(10) + 25(5) =
50 + 100 + 125 = 275


logarithm/323190: I need help doing this problem. Thank you
6^2t=7200
1 solutions

Answer 231352 by ankor@dixie-net.com(15649) About Me  on 2010-07-17 15:54:18 (Show Source):
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Assume it's 6%5E%282t%29 = 7200
log%286%5E%282t%29%29 = log%287200%29
2t*log(6) = log(7200)
:
.77815(2t) = 3.857
:
1.5563t = 3.857
t = 3.857%2F1.5563
t = 2.4783
:
:
Check solution on a calc, enter: 6^(2*2.4783) = 7194 ~ 7200


Numbers_Word_Problems/323053: One number is 3 less than another. If 4 times the smaller number minus 3 times the larger number is 4, find the two numbers.
1 solutions

Answer 231289 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 21:53:58 (Show Source):
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let x = "One number"
let y = "another number"
:
One number is 3 less than another.
x = y - 3
:
If 4 times the smaller number minus 3 times the larger number is 4,
4x - 3y = 4
:
find the two numbers.
Replace x with (y-3)
4(y-3) - 3y = 4
4y - 12 - 3y = 4
4y - 3y = 4 + 12
y = 16
:
I'll let you find x


Equations/322943: Find the values of x and y that solve the following system of equations:
8x+7y=12
-7x-4y=-2
1 solutions

Answer 231285 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 21:40:40 (Show Source):
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+8x + 7y = 12
-7x - 4y = -2
:
Multiply the 1st equation by 4, multiply the 2nd equation by 7, results
+32x + 28y = 48
-49x - 28y = -14
---------------------addition eliminates y, find x
-17x + 0y = 34
x = 34%2F%28-17%29
x = -2
:
Use the 1st original equation to find y
8(-2) + 7y = 12
-16 + 7y = 12
7y = 12 + 16
7y = 28
y = 28%2F7
y = 4
:
:
Check solution in the 2nd original equation:
-7(-2) - 4(4) = -2
14 - 16 = -2


Polynomials-and-rational-expressions/323035: t^3w^2x^4 and 5t^7x
Can you help me find the least common multipleof these two expressions, then simplify as much as possible?
1 solutions

Answer 231282 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 21:23:50 (Show Source):
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t^3w^2x^4 and 5t^7x
Can you help me find the least common multiple of these two expressions, then simplify as much as possible?
:
Write an expression which include the term with the highest exponent
5t%5E7%2Aw%5E2%2Ax%5E4


Miscellaneous_Word_Problems/322918: The desks in a classroom are arranged in straight rows. John is in the third
row from the front and the fourth row from the back. He is also third from
the left end of a row and fifth from the right. How many desks are in the classroom?
1 solutions

Answer 231261 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 19:14:47 (Show Source):
You can put this solution on YOUR website!
The desks in a classroom are arranged in straight rows.
John is in the third row from the front and the fourth row from the back.
He is also third from the left end of a row and fifth from the right.
How many desks are in the classroom?
:
No. of rows:
3 + 4 = 7 but John's row can only be counted once, rows = 6
No. of desk in a row. 3 + 5 = 8 but John's desk counted only once, desk = 7
Therefore:
6 * 7 = 42 desks in the classroom
:
like this
o o o o o o o
o o o o o o o
o o x o o o o
o o o o o o o
o o o o o o o
o o o o o o o


Polynomials-and-rational-expressions/322942: The question is (p^2q^2/p^-4q^5)^-3. Can you help?
1 solutions

Answer 231243 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 16:45:11 (Show Source):
You can put this solution on YOUR website!
Assume the question is %28%28p%5E2q%5E2%29%2F%28p%5E-4q%5E5%29%29%5E-3 and you want to simplify.
:
Combine the like terms to give us positive exponents if possible
%28%28p%5E%282%2B4%29%29%2F%28q%5E%285-2%29%29%29%5E-3 = %28%28p%5E6%29%2F%28q%5E3%29%29%5E-3
The reciprocal gets rid of the neg exponent
%28%28q%5E3%29%2F%28p%5E6%29%29%5E3
multiply exponents by 3
q%5E9%2Fp%5E18


Geometry_Word_Problems/322961: A cylindrical drum has a diameter of 3 feet and stands 5 feet high. What is the volume of the drum? (Hint: Use
1 solutions

Answer 231237 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 16:30:05 (Show Source):
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: A cylindrical drum has a diameter of 3 feet and stands 5 feet high.
What is the volume of the drum?
:
A diameter of 3 ft gives us a radius of 1.5 ft
:
Formula for the volume of cylinder:
V+=+pi%2Ar%5E2%2Ah
:
Substitute for r and h, to find V
V+=+pi%2A1.5%5E2%2A5


Triangles/322909: how do i calculate the height of a triangle if i have too angles and the length of the base ?
1 solutions

Answer 231232 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 16:25:32 (Show Source):
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how do i calculate the height of a triangle if i have too angles and the length of the base ?
Briefly
1.Find the third angle by subtracting the two from 180 degrees
:
2.Find one of the other sides using the law of sines
That side will be the hypotenuse of the right triangle formed by the height
:
3. Use the sine of one of the given angles to find the height


Expressions-with-variables/322959: Solve for x:
4x(x-6)-5x(x-5)= -2
Simplify and use comma to separate answers.
thannk you for your help.
1 solutions

Answer 231229 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 16:17:55 (Show Source):
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Solve for x:
4x(x-6) - 5x(x-5) = -2
Multiply to eliminate the brackets
4x^2 - 24x - 5x^2 + 25x = -2
Combine like terms
4x^2 - 5x^2 - 24x + 25x + 2 = 0
:
-x^2 + x + 2 = 0
Easier to factor if we change the signs, multiply by -1
x^2 - x - 2 = 0
Factors to
(x-2)(x+1) = 0
Two solutions
x = 2
x = -1
:
x: 2, -1
:
:
Confirm our solution using x=-1, in the original problem
4(-1)(-1-6) - 5(-1)(-1-5) = -2
-4(-7) - (-5) (-6) = -2
+28 + 5(-6) = -2
28 - 30 = -2; confirms our solution of x=-1
:
You should confirm the solution x=2, in the same manner


Linear-equations/323011: Train A and B are traveling in the same direction on parallel tracks. Train A is traveling at 40mph and train b is traveling at 50 mph. Train A passes a station at 11:15 pm. If train B passes the same station at 11:45pm, at what time will train B catch up to train A?
1 solutions

Answer 231216 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 15:22:05 (Show Source):
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Train A and B are traveling in the same direction on parallel tracks.
Train A is traveling at 40mph and train B is traveling at 50 mph.
Train A passes a station at 11:15 pm.
If train B passes the same station at 11:45pm, at what time will train B catch up to train A?
:
from the given information, we know that train B is 30 min (1/2 hr) behind
train A, when train A passes the station
:
The distance between the trains at this time: 1%2F2 * 50 = 25 mi
:
Let t = time required for train B to catch train A
:
write a distance equation: Dist = speed * time
:
Train B travel dist = Train A travel dist + 25 mi
50t = 40t + 25
50t - 40t = 25
10t = 25
t = 25%2F10
t = 2.5 hr or 2 hr 30 min
:
11:45 pm + 2:30 = 2:15 am, B catches A


Radicals/322952: Subtract. Simplify by collecting like radical terms if possible.
5 square root of 18 - 7 square root of 2 =
Simpify and use radicals as needed.
Thanks for your help.
1 solutions

Answer 231214 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 14:45:33 (Show Source):
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Simplify by collecting like radical terms if possible.
5 square root of 18 - 7 square root of 2 =
Simplify and use radicals as needed.
:
5sqrt%2818%29+-+7sqrt%282%29
Factor inside the 1st radical to reveal a perfect square
5sqrt%289%2A2%29+-+7sqrt%282%29
Extract that perfect square
5%2A3sqrt%282%29+-+7sqrt%282%29
:
15sqrt%282%29+-+7sqrt%282%29
Now we have like terms, just do the math, and we have:
8sqrt%282%29
:
:
Check this on your calc: enter: 5sqrt%2818%29+-+7sqrt%282%29 = 11.313
and enter 8sqrt%282%29 = 11.313 also


Polynomials-and-rational-expressions/323000: According to the Einstein’s Theory of Relativity, nothing in the universe as we presently know it can exceed the speed of light; in a sense, it is the ultimate cosmic speed limit. Speed of light in vacuum is 300,000 kilometers/second or 671,080,888 miles/hour! Take a moment and think about this tremendously high speed; it is extremely fast; faster than a speeding bullet (speed of a rifle bullet is in the range 400 to 3,350 miles/hour). a) Show the speed of light in scientific notation in units of miles/hr. b) Given that Moon on average is 240,000 miles away from where you are standing on Earth, how long does it take a light ray to travel from the Earth to the Moon?
1 solutions

Answer 231213 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 14:19:35 (Show Source):
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a) Show the speed of light in scientific notation in units of miles/hr.
6.71(10^8) mi/hr
:
:
b) Given that Moon on average is 240,000 miles away from where you are standing on Earth, how long does it take a light ray to travel from the Earth to the Moon?
:
Convert to miles per second
671080888%2F3600 = 186,411.358 mi/sec
:
240000%2F186411.358 = 1.287 sec


Miscellaneous_Word_Problems/322955: Two positive numbers differ by 6, and their squares differ by 96. Find the numbers.
1 solutions

Answer 231211 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 13:56:18 (Show Source):
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Two positive numbers differ by 6,
x - y = 6
x = (y+6)
:
and their squares differ by 96.
x^2 - y^2 = 96
:
replace x with (y+6)
(y+6)^2 - y^2 = 96
:
FOIL (y+6)(y+6)
y^2 + 12y + 36 - y^2 = 96
:
Combine like terms
y^2 - y^2 + 12y = 96 - 36
:
12y = 60
y = 60%2F12
y = 5
then
x = 5 + 6
x = 11
:
:
Check solution by finding the squares
11^2 - 5^2 = 96


Travel_Word_Problems/322988: John and Tony start from the same place at the same time and head for a town 10 miles away. John walks twice as fast as Tony and arrives 3 hours before Tony. Find the speed of each.

1 solutions

Answer 231203 by ankor@dixie-net.com(15649) About Me  on 2010-07-16 13:21:59 (Show Source):
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John and Tony start from the same place at the same time and head for a town 10 miles away.
John walks twice as fast as Tony and arrives 3 hours before Tony. Find the speed of each.
:
Let s = Tony's walking speed
then
2s = John's walking speed
:
Write a time equation: Time = dist/speed
:
John's time + 3 hrs = Tony's time
10%2F%282s%29 + 3 = 10%2Fs
multiply by 2s, results:
10 + 2s(3) = 2(10)
10 + 6s = 20
6s = 20 - 10
6s = 10
s = 10%2F6
s = 12%2F3 mph is Tony's speed
then
2(12%2F3) = 31%2F3 is John's speed
:
:
Check solution with a calc by finding the times
10/1.67 ~ 6 hrs
10/3.33 ~ 3 hrs; a 3 hr difference


Quadratic_Equations/322818: A rectangular playground 40m by 60m is to be doubled in area by extending the length and width by an equal amount. By how much should the length and the width be lengthened?
1 solutions

Answer 231114 by ankor@dixie-net.com(15649) About Me  on 2010-07-15 20:10:07 (Show Source):
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A rectangular playground 40m by 60m is to be doubled in area by extending the
length and width by an equal amount.
By how much should the length and the width be lengthened?
:
Find the area of the present playground
40 * 60 = 2400 sq/m
then
2*2400 = 4800 sq/m is the new area
:
Let x = amt to extend the length and the width
(x+40)*(x+60) = 4800
FOIL
x^2 + 60x + 40x + 2400 = 4800
A quadratic equation
x^2 + 100x + 2400 - 4800 = 0
x^2 + 100x - 2400 = 0
Factors to
(x+120)(x-20) = 0
The positive solution
x = 20 m, to extend dimensions to double the area
;
:
See if that's true, find the area with the new dimensions
60 * 80 = 4800


Quadratic_Equations/322751: A rectangular field is to be enclosed by a fence and then divded into two small plots by a fence parallel to one of the sides. If thre is 1800 m of fencing available, find the dimensions of the field that will give the maximum area.
1 solutions

Answer 231104 by ankor@dixie-net.com(15649) About Me  on 2010-07-15 19:46:08 (Show Source):
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A rectangular field is to be enclosed by a fence and Ithen divided into two
small plots by a fence parallel to one of the sides.
If there is 1800 m of fencing available, find the dimensions of the field that will give the maximum area.
:
2L + 3W = 1800
2L = 1800-3W
Divide both sides by 2
L = (900-1.5W)
:
Area = L * W
Replace L with (900-1.5W)
A = W(900-1.5W)
A = -1.5W^2 + 900W
Find the axis of symmetry, x=-b/(2a); in this equation: a=-1.5, b=900
W = %28-900%29%2F%282%2A-1.5%29
W = %28-900%29%2F%28-3%29
W = +300 m is the width for max area
then
L = 900 - 1.5(300)
L = 450 m is the length
and
300 * 450 = 135,000 sq/m is max area


Miscellaneous_Word_Problems/322806: Find a number which is decreased by 54 and is 5 times its opposite?
1 solutions

Answer 231094 by ankor@dixie-net.com(15649) About Me  on 2010-07-15 19:06:58 (Show Source):
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Find a number which is decreased by 54 and is 5 times its opposite?
:
Let x = "a number
then
-x = it's opposite
:
x - 54 = 5(-x)
x - 54 = -5x
x + 5x = +54
6x = 54
x = 54%2F6
x = 9
;
;
Check solution in original statement
9 - 54 = 5(-9)
-45 = -45


Linear_Equations_And_Systems_Word_Problems/322644: 1n 2005,a father was 4 times as old as his son.in the year 2015,thrice the son's age will exceed the father's age by ten years,in which year was the son born?
1 solutions

Answer 231093 by ankor@dixie-net.com(15649) About Me  on 2010-07-15 18:59:24 (Show Source):
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1n 2005, a father was 4 times as old as his son.
In the year 2015,thrice the son's age will exceed the father's age by ten
years, in which year was the son born?
:
In 2005, let; f = father's age, s = son's age:
f = 4s
:
In 2015:
f + 10 = 3(s+10) - 10
f + 10 = 3s + 30 - 10
f + 10 = 3s + 20
f = 3s + 20 - 10
f = 3s + 10
Replace f with 4s, find s:
4s = 3s + 10
4s - 3s = 10
s = 10 yrs old in 2005
Son was born in 1995
:
:
Check solution, fathers age in 2005, 4(10) = 40
In 10 yrs
40 + 10 = 3(10+10) - 10
50 = 3(20) - 10


Linear-systems/322627: why is it that in diff places you do not reciprocate the values that you need to eliminate?for example 1x+2y=3
2x+1y=3 then if youre trying to eliminate y or get it it becomes 1(1x+2y=3)
2(2x+1y=3)then becomes x+2=3
4x+2y=6
1 solutions

Answer 231077 by ankor@dixie-net.com(15649) About Me  on 2010-07-15 17:52:47 (Show Source):
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why is it that in diff places you do not reciprocate the values that you need to eliminate?for example 1x+2y=3
2x+1y=3 then if youre trying to eliminate y or get it it becomes 1(1x+2y=3)
2(2x+1y=3)then becomes x+2=3
4x+2y=6
:
I am not sure what you are trying to say here,
but if you want to solve the following by eliminating y:
:
1x + 2y = 3
2x + 1y = 3
Multiply the 2nd equation by 2 and you have
1x + 2y = 3
4x + 2y = 6
-------------subtracting eliminates y, find x
-3x = -3
x = %28-3%29%2F%28-3%29
x = +1
:
Find y using the 1st equation
1 + 2y = 3
2y = 3 - 1
2y = 2
y = 2%2F2
y = +1
:
Check solution in the 2nd original equation
2(1) + 1 = 3


Problems-with-consecutive-odd-even-integers/322593: The product of four different positive integers is 360. what is the maximum possible sum of these four integers ?
1 solutions

Answer 231061 by ankor@dixie-net.com(15649) About Me  on 2010-07-15 17:06:14 (Show Source):
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The product of four different positive integers is 360.
what is the maximum possible sum of these four integers ?
:
Find the 4th root of 360
360%5E%281%2F4%29 = 4.35.......
integers above and below this value
3 * 4 * 5 * 6 = 360
:
3 + 4 + 5 + 6 = 18 is max


Quadratic_Equations/322752: Ethan cuts half a rectangular lawn 40 m by 30 m by mowing a strip of equal width around the perimeter. Julia cuts the small rectangle left. How wide a strip does Ethan cut so that they share the work equally?
1 solutions

Answer 231059 by ankor@dixie-net.com(15649) About Me  on 2010-07-15 16:56:23 (Show Source):
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Ethan cuts half a rectangular lawn 40 m by 30 m by mowing a strip of equal width around the perimeter.
Julia cuts the small rectangle left.
How wide a strip does Ethan cut so that they share the work equally?
:
Let x = the width of the strip cut by E
:
Find the total area of the lawn; 40 * 30 = 1200 sq/m
Each will mow an area of 600 sq/m
:
Dimension of the small rectangle which is 600 sq/ft:
(40-2x) by (30-2x)
;
Write an area equation of this rectangle. find x, which is the width of the strip
(40-2x)(30-2x) = 600
FOIL
1200 - 80x - 60x + 4x^2 = 600
Arrange as a quadratic equation
4x^2 - 140x + 1200 - 600 = 0
4x^2 - 140x + 600 = 0
Simplify divide by 4
x^2 - 35x + 150 0 =
Factor
(x - 5)(x - 30) = 0
The reasonable solution
x = 5 ft is the width of the strip
:
:
Check solution by finding the area of the inside rectangle
(40-10)*(30-10) = 600


Geometry_Word_Problems/321933: triangle has a perimeter of 36 centimeters. If the length of each side is increased by 50%
1 solutions

Answer 230655 by ankor@dixie-net.com(15649) About Me  on 2010-07-13 19:25:47 (Show Source):
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triangle has a perimeter of 36 centimeters.
If the length of each side is increased by 50%
:
Assume it is an equilateral triangle, each side 36/3 = 12
Increase each side by 50%, 18 cm, new perimeter, 3*18 = 54 cm


Miscellaneous_Word_Problems/321711: Phone was thrown from top of a building. The height h(t) of the cell phone at time (t) is described by the function h(t) = -16tsquared +96t+112. When will the phone be at a height of 192 feet and how many seconds will it take to hit the ground?
I have tried putting the numbers in and just cannot figure this out. Can you help please? Thanks
1 solutions

Answer 230425 by ankor@dixie-net.com(15649) About Me  on 2010-07-12 19:54:32 (Show Source):
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Phone was thrown from top of a building.
The height h(t) of the cell phone at time (t) is described by the function h(t) = -16tsquared +96t+112.
When will the phone be at a height of 192 feet and how many seconds will it take to hit the ground?
:
-16t^2 + 96t + 112 = h(t)
The phone will be at 192 ft when h(t) = 192
-16t^2 + 96t + 112 = 192
Subtract 192 from both sides
-16t^2 + 96t + 112 - 192
-16t^2 + 96t - 80 = 0; a quadratic equation
Simplify, and change the signs, divide each term by -16
t^2 - 6t + 5 = 0
Factors to
(t - 5)(t + 1) = 0
The positive solution
t = 5 sec , tel at 192 ft
:
Phone will hit the ground when h(t) = 0
-16t^2 + 96t + 112 = 0
Simplify again, divide by -16
t^2 - 6t - 7 = 0
Factors to
(t - 7)(t + 1) = 0
positive solution
t = 7 sec, phone strikes the ground


Linear_Equations_And_Systems_Word_Problems/321836: Bob received $14,000 inheritance and divided it between a mutual fund that yielded a yearly return of 5% and a 1-year CD that paid 3.5% annually. If his total earnings for the year on this investment was $640, how much did he invest in each of these two funds?
1 solutions

Answer 230414 by ankor@dixie-net.com(15649) About Me  on 2010-07-12 19:03:23 (Show Source):
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Bob received $14,000 inheritance and divided it between a mutual fund that
yielded a yearly return of 5% and a 1-year CD that paid 3.5% annually.
If his total earnings for the year on this investment was $640, how much did
he invest in each of these two funds?
:
Let x = amt invested at 5%
The total was given as 14000, therefore
(14000-x) = amt invested at 3.5%
:
Write a total interest equation in decimal form
.05x + .035(14000-x) = 640
:
.05x + 490 - .035x = 640
:
.05x - .035x = 640 - 490
:
.015x = 150
x = 150%2F.015
x = $10,000 amt invested at 5%
:
I'll let you find out the amt invested a 3.5%
:
Check solution by finding the total interest using the two values


Quadratic_Equations/321789: Write a quadratic equation in the variable x having the given numbers as solutions. Type the equation in standard form, ax^2 + bx + c = 0
Problem:
Solution: 2, (only solution)
Thank you!!
1 solutions

Answer 230405 by ankor@dixie-net.com(15649) About Me  on 2010-07-12 18:11:07 (Show Source):
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Write a quadratic equation in the variable x having the given numbers as solutions. Type the equation in standard form, ax^2 + bx + c = 0
Problem:
Solution: 2, (only solution)
:
A solution of 2 will come from factors: (x-2), (x-2)
FOIL (x-2)(x-2) = x^2 - 4x + 4 = 0


Linear_Equations_And_Systems_Word_Problems/321698: . Suppose you have a lemonade stand, and when you charge $1 per cup of lemonade you sell 60 cups. But when you raise your price to $1.50 you only sell 30 cups. Write an equation for the number of cups you sell as a function of the price you charge. Denote "C" for number of cups, and "P" for the price you charge. Assume the function is linear.
1 solutions

Answer 230400 by ankor@dixie-net.com(15649) About Me  on 2010-07-12 17:20:14 (Show Source):
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you charge $1 per cup of lemonade you sell 60 cups.
But when you raise your price to $1.50 you only sell 30 cups
Write an equation for the number of cups you sell as a function of the price you charge.
Denote "C" for number of cups, and "P" for the price you charge
:
the slope of the equation: m = %28y2-y1%29%2F%28x2-x1%29
Assign the given values as follows:
x1=1.00, y1=60
x2=1.50, y2=30
Find the slope
m = %2830-60%29%2F%281.5-1%29 = %28-30%29%2F.5 = -60 is the slope
:
Use the point/slope formula: y - y1 - m(x - x1)
y - 60 = -60(x - 1)
y - 60 = -60x + 60
y = -60x + 60 + 60
y = -60x + 120
:
c = -60p + 120, is the equation


Numbers_Word_Problems/321696: Three consecutive whole numbers are such that the square of the middle number is greater than the product of the other two by 1. Find the middle number
1 solutions

Answer 230399 by ankor@dixie-net.com(15649) About Me  on 2010-07-12 17:08:00 (Show Source):
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Three consecutive whole numbers are such that the square of the middle number
is greater than the product of the other two by 1.
Find the middle number:
There is no unique solution
:
let x = the middle number
then
(x-1) = the 1st number
and
(x+1) = the 3rd number
:
x^2 = ((x-1)*(x+1)) + 1
FOIL
x^2 = x^2 - 1 + 1
:
x^2 = x^2
Which means this is true for any 3 consecutive numbers even, -1, 0 +1
:
Try a few like; 142, 143, 144: 143^2 = 20449, 142*144 = 20448