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Maths68 answered: 1474 problems
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Travel_Word_Problems/520806: Two planes leave the airport at the same time. One flies directly east at 540 miles per hour. The other flies west at 720 miles per hour. How long will it take them to be 1890 miles apart?
1 solutions

Answer 346239 by Maths68(1474) About Me  on 2011-10-25 13:00:03 (Show Source):
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Effective Speed = 540+720 = 1260 mph
Distance = 1890 miles
Time = Distance / Speed
Time = 1890/1260
time = 1.5 hour.

After 1.5 hours two planes will be 1890 miles apart?


Check
======
Plane A Data
============
Speed = 540 mph
Time = 1.5 hour
Distance covered = ?
Distance = Speed * Time
Distance covered= 540 * 1.5 = 810 miles

Plane B Data
============
Speed = 720 mph
Time = 1.5 hour
Distance covered = ?
Distance = Speed * Time
Distance covered = 720 * 1.5 = 1080 miles

Total Distance between two planes after 1.5 hours = 1080+810 = 1890 miles


Equations/520858: Half the number y is equal to y minus ten.
1 solutions

Answer 346238 by Maths68(1474) About Me  on 2011-10-25 12:43:12 (Show Source):
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Half the number y is equal to y minus ten.
1/2(y)=y-10
y/2=y-10
2*(y/2)=2*(y-10)
y=2y-20
y-2y=-20
-y=-20
Multiply by -1 both sides
y=20


Graphs/520792: find equestion of the line which is perpindicular the line y=5x+9 and has y-intercept=6
1 solutions

Answer 346235 by Maths68(1474) About Me  on 2011-10-25 12:24:07 (Show Source):
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find equestion of the line which is perpindicular the line y=5x+9 and has y-intercept=6
Given
y=5x+9
Compare above equatoin with Standard Equation of the Straight line
y=mx+b
Slope m = 5
Since lines are perpendicular, multiplication of their slopes will result in (-1) therefore slope of the required line is (-1/5) and we have been given y-intercept 6 of the required line
y=-(1/5)x+6
y=-x/5+6
Above equation is the equatoin of the required line.
Red line = Given Line
Green line = Required Line
+graph%28+500%2C+500%2C+-10%2C+10%2C+-10%2C+10%2C+y=5x%2B9%2Cy=-x%2F5%2B6+%29+


Age_Word_Problems/520238: John is 10 years older than Chris. In 2 years John will be twice as old as Chris. How old are they now?
1 solutions

Answer 346199 by Maths68(1474) About Me  on 2011-10-25 07:51:37 (Show Source):
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Let
Present age of John = j
Present age of Chris = c

John is 10 years older than Chris.
j=c+10 ..........(1)
In 2 years
John will be = j + 2
Chris will be = c + 2
Then,
John will be twice as old as Chris.
j + 2 = 2(c + 2)
j + 2 = 2c + 4
j = 2c + 4 - 2
J = 2c + 2 .............(2)
Put the value of j from (1) to (2)
c+10 = 2c + 2 .............(2)
c-2c=2-10
-c=-8
Multiply by -1 both sides
c=8
Put the value of c in (1)
j = 8 + 10
j = 18



Present age of John = j = 18 years old
Present age of Chris = c = 8 years old


Age_Word_Problems/520289: Dorthy is 14 years youngfer than Rita. Ten years ago Rita was 3 times as old as Dorthy was then. How old is each now?
1 solutions

Answer 346198 by Maths68(1474) About Me  on 2011-10-25 07:45:19 (Show Source):
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Let
Present age of Dorthy = d
Present age of Rita = r

Dorthy is 14 years younger than Rita.
d=r-14.........(1)
Ten years ago
Dorthy age was = d-10
Rita age was = r-10
Then,
Rita was 3 times as old as Dorthy
r-10=3(d-10)
r-10=3d-30
r=3d-30+10
r=3d-20...........(2)
Plug in the value of d from (1) to (2)
r=3(r-14)-20
r=3r-42-20
r-3r=-62
-2r=-62
-2r/-2=-62/-2
r=31
Pulg in the value of r in (1)
d=r-14
d=31-14
d=17


Present age of Dorthy = d = 17 years old
Present age of Rita = r = 31 years old



Age_Word_Problems/520370: Six years ago,bill was 1/4 as old as he is now.How old is bill?
1 solutions

Answer 346189 by Maths68(1474) About Me  on 2011-10-25 05:26:29 (Show Source):
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Let
Present age of Bill = x
Six year ago he was = x-6
Then
Bill was 1/4 of his present age
1/4x=x-6
x/4=x-6
x=4(x-6)
x=4x-24
x-4x=-24
-3x=-24
-3x/-3=-24/-3
x=8
Bill is 8 years old
Check
======
Bill present age 8 years
Six years ago = 8-6 = 2 (which is 1/4 of 8)


Money_Word_Problems/520695: A businessman borrowed from two moneylenders a sum of rs 2000.for 1 loan the rate of simple interest was 8% Pa and the other was 6 % pa he paid total interest of rs 136 for one year .find the sum borrowed on each rate by him ?
1 solutions

Answer 346188 by Maths68(1474) About Me  on 2011-10-25 05:18:23 (Show Source):
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Amount taken at 8% = x
Amount taken at 6% = 2000-x
Total interest paid = 136



Amount taken * interest rate + Amount taken * interest rate = Total interest paid
x*8% + (2000-x)*6% = 136
x*8/100 + (2000-x)*6/100 = 136
Multiply by 100 both sides
x*8 + (2000-x)*6 = 136 * 100
8x + 12000-6x=13600
8x - 6x=13600-12000
2x=1600
2x/2=1600/2
x=800


Amount taken at 8% = x = 800
Amount taken at 6% = 2000-x = 2000-800 = 1200

Check
800 * 8/100 + 1200 * 6/100 = 136
8*8 + 12*6 = 136
64+72 = 136
136=136


Problems-with-consecutive-odd-even-integers/520673: The product of two consecutive odd whole numbers is one less than five times their sum. Find the whole numbers
1 solutions

Answer 346166 by Maths68(1474) About Me  on 2011-10-25 01:10:45 (Show Source):
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Let
One odd integer = x+1
Other odd integer = x+3
Given Condition
(x+1)(x+3)=5((x+1)+(x+3))-1
x^2+3x+x+3=5(x+1+x+3)-1
x^2+4x+3=5(2x+4)-1
x^2+4x+3=10x+20-1
x^2+4x+3=10x+19
x^2+4x-10x+3-19=0
x^2-6x-16=0
x^2-8x+2x-16=0
x(x-8)+2(x-8)=0
(x-8)(x+2)=0
x-8=0 or x+2=0
x=8 or x=-2 (inadmissible)
x=8
One odd integer = x+1 = 8+1=9
Other odd integer = x+3 = 8+3 = 11
Check
======
Product of integers = 5 (sum of integers) -1
9*11=5(9+11)-1
99=5(20)-1
99=100-1
99=99




Average/520672: two investments were made totaling 8800 dollars. for a certain year these investments yielded 1326 dollars in simple intrest. part of the 8800 was ivested at 14% and part at 16%. Find the amount invested in each rate
1 solutions

Answer 346165 by Maths68(1474) About Me  on 2011-10-25 00:34:01 (Show Source):
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Let
Amount invested at 14% = x
Amount invested at 16% = 8800-x
Given
Total interest on both investments = 1326
14% * (x) + 16% * (8800-x) = 1326
14/100 * (x) + 16/100 * (8800-x) = 1326
Multiply by 100 both sides
14 * (x) + 16 * (8800-x) = 1326 * 100
14x + 140800-16x = 132600
-2x=132600-140800
-2x=-8200
-2x/-2=-8200/-2
x=4100
Amount invested at 14% = x = 4100
Amount invested at 16% = 8800-x = 8800-4100 = 4700

Check
=====
4100 * 14/100 + 4700 * 16/100 = 1326
Multiply by 100 both sides
4100*14 + 4700*16 = 132600
57400+75200=132600
132600=132600


Money_Word_Problems/520618: A dealer bought some radios for a total of $1,080. She gave away 9 radios as gifts, sold the rest for $10 more than she paid for each radio, and broke even. How many radios did she buy?
1 solutions

Answer 346163 by Maths68(1474) About Me  on 2011-10-25 00:10:58 (Show Source):
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Let
She bought = x radios
Price per radio = 1080/x
Number of Radio Gifted = 9
She sold = x-9
She sold $10 more than the original price = 1080/x + 10
Total Amount radios sold = (1080/x+10)*(x-9) = 1080-9720/x+10x-90 = (10x-9720/x+990)

Finally she broke even
Total amount radio sold = Final Amount
10x-9720/x+990 = 1080
10x-9720/x = 1080 - 990
10x-9720/x = 90
Multiply by x both sides
10x^2-9720= 90x
10x^2-90x-9720=0
10*(x^2-9x-972)=0
Divide by 10 both sides
x^2-9x-972=0
x^2-36x+27x-972=0
x(x-36)+27(x-36)
x-36=0 or x+27=0
x=36 or x=-27 (inadmissible)
She bought 36 radios
Price per radio = 1080/36 = 30
She sold = 36-9 = 27 radios
She sold 27 radios for $10 more than she paid for each radio = 30+10=40
Total Amount she received for selling 27 radios @ $40 = 27*40 = $1080






Complex_Numbers/520586: how to solve x+3y=11,x+4y=14
1 solutions

Answer 346142 by Maths68(1474) About Me  on 2011-10-24 22:35:38 (Show Source):
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x+4y=14 ..........(1)
x+3y=11 ..........(2)
Subtract (2) from (1)
x+4y=14
-x-3y=-11
--------------
y=3
Plug in the value of y in (1)
x+4y=14
x+4(3)=14
x+12=14
Subtract 12 from both sides
x+12-12=14-12
Cancel out 12 from Left Hand Side (LHS)
x=2
x,y = 2, 3


Check
======
Plug in the values of x and y in (1)
x+4y=14 ..........(1)
2+4(3)=14
2+12=14
14=14
Now
Plug in the values of x and y in (2)
x+3y=11 ..........(2)
2+3(3)=11
2+9=11
11=11


test/520605: 2r-6=0
1 solutions

Answer 346137 by Maths68(1474) About Me  on 2011-10-24 22:24:38 (Show Source):
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2r-6=0
Add 6 both sides
2r-6+6=6
Cancel out 6 from LHS
2r=6
divide by 2 both sides
2r/2=6/2
r=3


Check
======
2r-6=0
2(3)-6=0
6-6=0
0=0


Exponents/520600: I am suppose to reduce
15x^3/6x^-3
Would the answer be 5x^6/2 ?
1 solutions

Answer 346132 by Maths68(1474) About Me  on 2011-10-24 22:18:51 (Show Source):
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Yes, you are right.
Answer is 5x^6/2

Solved by pluggable solver: EXPLAIN simplification of an expression
Your Result:


YOUR ANSWER


  • Here's what you tried:
  • Graphical form: 15x%5E3%2F6%2Fx%5E-3 simplifies to 5%2Ax%5E%286%29%2F2
  • Text form: 15x^3/6/x^-3 simplifies to 5*x^(6)/2
  • Cartoon (animation) form: simplify_cartoon%28+15x%5E3%2F6%2Fx%5E-3+%29
    For tutors: simplify_cartoon( 15x^3/6/x^-3 )
  • If you have a website, here's a link to this solution.

DETAILED EXPLANATION


Look at highlight_red%28+15+%29%2Ax%5E3%2Fhighlight_red%28+6+%29%2Fx%5E-3.
Factors 15 and 6 have greatest common factor (GCF) of 3. Reducing fraction.
It becomes highlight_green%28+5+%29%2Ax%5E3%2Fhighlight_green%28+2+%29%2Fx%5E-3.

Look at 5%2Ahighlight_red%28+x%5E3+%29%2F2%2Fhighlight_red%28+x%5E-3+%29.
Reduce similar several occurrences of highlight_red%28+x%5E3+%29 to highlight_green%28+x%5E%283--3%29+%29
It becomes 5%2Ahighlight_green%28+x%5E%283--3%29+%29%2F2.

Look at 5%2Ax%5E%283-highlight_red%28+-3+%29%29%2F2.
Removed extra sign in front of 3
It becomes 5%2Ax%5E%283%2Bhighlight_green%28+3+%29%29%2F2.

Look at 5%2Ax%5E%28highlight_red%28+3+%29%2Bhighlight_red%28+3+%29%29%2F2.
Added fractions or integers together
It becomes 5%2Ax%5E%28highlight_green%28+6+%29%29%2F2.
Result: 5%2Ax%5E%286%29%2F2

Universal Simplifier and Solver


Done!




Pythagorean-theorem/520172: if you have a right triangle that has a height of 5cm and length of 6cm what is the length of the diagonal
1 solutions

Answer 345950 by Maths68(1474) About Me  on 2011-10-24 12:57:23 (Show Source):
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a = 5cm
b = 6cm
c = ?
Use Pythagorean Theorem
c^2=a^2+b^2
c^2=(5)^2+(36)^2
c^2 = 25 +36
c^2 = 61
Taking sqrt both sides
sqrtc^2 = sqrt61
c=7.81cm
The length of diagonal is 7.81cm


Linear-equations/520131: find the equation for the line that is parallel to the line wih the equation (y+2)=1/2 (x-4) passing through the point (1,3)
1 solutions

Answer 345949 by Maths68(1474) About Me  on 2011-10-24 12:49:05 (Show Source):
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Standard Form of Equation of the line:
y=mx+b
Given
(y+2)=1/2 (x-4)
rearrage the above equation according to the standard form
y+2=(1/2)x-4(1/2)
y+2=(1/2)x-2
y=(1/2)x-2-2
y=(1/2)x-4
Compare above equation with the standard form equation
m=1/2 and b=-4
Since lines are parallel their slopes will be equal,therefore slope of the required line will be (1/2)
Now we have a point(1,3) and slope (1/2)of the line we can easily find required lines by putting these values in the equation of the straight line poin-slope form.
m=(y2-y1)/(x2-x1)
1/2=(y-3))/(x-1)
1*(x-1)=2(y-3)
x-1=2y-6
x-1+6=2y
x+5=2y
2y=x+5
2y/2=(x+5)/2
y=(1/2)x+5/2
Above equation is the Equation of Staright line in the Standard Form.


test/520144: Ce nter City East Parking Garage has a capacity of 251 cars more than Center City West Parking Garage. If the combined capacity for the two garages is 1221 cars, find the capacity for each garage
1 solutions

Answer 345943 by Maths68(1474) About Me  on 2011-10-24 12:30:09 (Show Source):
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Ce nter City East Parking Garage has a capacity of 251 cars more than Center City West Parking Garage. If the combined capacity for the two garages is 1221 cars, find the capacity for each garage
Let
The Capacity of Center City West Parking = x
The Capacity of Center City East Parking = x + 251
Parking Capacity of Both Centres = Total Parking Capacity
x+x+251=1221
2x+251=1221
2x=1221-251
2x=970
2x/2=970/2
x=485


The Capacity of Center City West Parking = x = 485
The Capacity of Center City East Parking = x + 251 = 485+251=736


Check
=====
Parking Capacity of Both Centres = Total Parking Capacity
485+736=1221
1221=1221


Exponents/520157: -3x+2=7x-22
1 solutions

Answer 345941 by Maths68(1474) About Me  on 2011-10-24 12:19:45 (Show Source):
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-3x+2=7x-22
-3x-7x=-22-2
-10x=-24
-10x/-10=-24/-10
x=12/5

Check
====
-3(12/5)+2=7(12/5)-22
(-36+10)/5=(84/5)-22
-26/5=(84-110)/5
-26/5=-26/5


Linear_Equations_And_Systems_Word_Problems/520149: A 68 foot pipe is cut into two pieces, one of the which is 12 ft less than the other.
What is the length of the shorter piece?
1 solutions

Answer 345938 by Maths68(1474) About Me  on 2011-10-24 12:11:18 (Show Source):
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A 68 foot pipe is cut into two pieces, one of the which is 12 ft less than the other.
What is the length of the shorter piece?
Let
One piece = x
Other piece = x-12
Sum of two pieces = Total length of entire piece
x+x-12=68
2x-12=68
2x=68+12
2x=80
x=80/2
x=40
One piece = x = 40 feet
Other piece = x-12 = 40-12 = 28 feet
Shorter piece = 28 feet


Geometry_Word_Problems/520153: The width of a rectangle is 4 more than the length,l. write an equation to describe the perimeter in term of w.
1 solutions

Answer 345935 by Maths68(1474) About Me  on 2011-10-24 12:04:53 (Show Source):
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The width of a rectangle is 4 more than the length,l. write an equation to describe the perimeter in term of w.

Perimeter = p
Lenght = l
Width = w
Given
l+4=w
l=w-4
Perimeter = p = 2 length + 2 width
p=2l+2w
p=2(w-4)+2w
p=2w-8+2w
p=4w-8
Perimeter in term of w


Money_Word_Problems/520137: Bernadette inherited $15,000 and invested it in two municipal bonds, which pay 7 percent and 9 percent simple interest. the annual interest is $1230. Find the amount at each rate.
1 solutions

Answer 345934 by Maths68(1474) About Me  on 2011-10-24 11:59:13 (Show Source):
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Let
Amount invested at 7% = x
Amount invested at 9% = 15000-x
Given
Total interest on both investments = 1230

7% * (x) + 9% * (15000-x) = 1230
7/100 * x + 9/100 * (15000-x) = 1230
Multiply by 100 both sides
7*x + 9 * (15000-x) = 1230 * 100
7x+ 135000-9x = 123000
7x-9x = 123000-135000
-2x=-12000
-2x/-2=-12000/-2
x=6000

Amount invested at 7% = x = 6000
Amount invested at 9% = 15000-x = 15000 - 6000 = 9000
Check
=====
6000 * 7/100 + 9000 * 9/100 = 1230
60*7 + 90*9 = 1230
420 + 810 = 1230
1230=1230



Money_Word_Problems/520138: A student takes out two loans, one at 5% interest and the other at 6% interest. The 5% loan is $1000 more than the 6% loan, and the total interest for 1 year is $215. How much is each loan?
1 solutions

Answer 345931 by Maths68(1474) About Me  on 2011-10-24 11:49:10 (Show Source):
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Let
Loan taken on 6% = x
Loan taken on 5% = x + 1000
Given
Total interest = 215

x*6% + (x+1000)*5% = 215
x*(6/100) + (x+1000)*(5/100) = 215
Multiply by 100 both sides
x*6 + (x+1000)*5=215*100
6x+5x+5000=21500
11x=21500 - 5000
11x=16500
11x/11=16500/11
x=1500

Loan taken on 6% = x = $1500
Loan taken on 5% = x + 1000 = 1500+1000 = $2500


Check
=====
1500 * 6/100 + 2500 * 5/100 = 215
15*6+25*5 = 215
90+125=215
215=215


Linear-equations/520112: 1. What is the slope of the line passing through the points (2, 7) and (–1, 3)?
1 solutions

Answer 345928 by Maths68(1474) About Me  on 2011-10-24 10:53:24 (Show Source):
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points (2, 7) and (–1, 3)
Slope of line = Rise in y / Rise in x
m = (y2-y1)/(x2-x1)
m=3-7/-1-2
m=-4/-3
m=4/3
Slope is 4/3


Geometry_Word_Problems/520103: A rectangular window has a length that is three times the width, the perimeter is 56 feet, find the length and width of the window
1 solutions

Answer 345927 by Maths68(1474) About Me  on 2011-10-24 10:50:38 (Show Source):
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Perimeter = P = 56
Length = l = 3w (Given)

Length = ?
Width = ?


Perimeter of rectangel = 2l + 2w

p = 2l + 2w
56 = 2(3w) + 2w
56 = 6w + 2w
56 = 8w
56/8=8w/8
7=w
w=7

Given
Length = l = 3w
Length = l = 3(7)
Length = 21


Perimeter = P = 56 ft.
Length = l = 21 ft.
Width = 7 ft



Complex_Numbers/520018: The attendance at a moving picture theater on a certain day was 737 persons. If there were 289 more adults than children, how children were there?
1 solutions

Answer 345914 by Maths68(1474) About Me  on 2011-10-24 05:09:15 (Show Source):
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Let
Number of Children = x
Number of Adults = x + 289
Adults + Children = 737
(x+289)+x=737
x+289+x=737
2x=737-289
2x=448
2x/2=448/2
x=224


Number of Children = x = 224
Number of Adults = x + 289 = 224+289=513

Check
======
Total Attendance = Adults + Children
737 = 513+224
737=737


Quadratic_Equations/520027: Determine the quadratic equation whose solutions are: 3 and -2

1 solutions

Answer 345913 by Maths68(1474) About Me  on 2011-10-24 04:57:55 (Show Source):
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Solution set = 3, -2
x= 3, or -2
x=3 or x=-2
x-3=0 or x+2=0
Since either of above is equal to zero, therefore multiplicatoin of the both will equal to zero
(x-3)(x+2)=0
x^2+2x-3x-6=0
x^2-x-6=0
Required Quadratic Equation.


Rectangles/519387: The area of a square rug in a library is 9
square feet.
What is the perimeter of the rug?
1 solutions

Answer 345904 by Maths68(1474) About Me  on 2011-10-24 02:18:41 (Show Source):
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Area of Square = side * side
Perimeter of Square = 4 * Side
Given
Area of Square = 9 sq ft.
side * side = 9
(side)^2=9
Take sqour root both sides
sqrt(side)^2=sqrt(9)
side=sqrt(3*3)
side=3 ft.
Perimeter of Square = 4 * Side
Perimeter of Square = 4 * 3
Perimeter of Square = 12 feet


Rectangles/519948: A garden is shaped like a rectangle whose perimeter is 88 ft. The length is 10 ft more than the width. Find the length and width.
1 solutions

Answer 345903 by Maths68(1474) About Me  on 2011-10-24 02:11:51 (Show Source):
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A garden is shaped like a rectangle whose perimeter is 88 ft. The length is 10 ft more than the width. Find the length and width.
P = 88 feet
L = W + 10
W = ?
L = ?
Perimeter of regtangle = 2 length + 2 width
P=2L + 2W
88 = 2 (W+10)+ 2W
88 = 2W+20+ 2W
88-20=4W
68=4W
68/4=W
17=W
W=17
Given
L=W+10 = 17+10 = 27 feet

Perimeter = 88 feet
Length = 27 feet
Width = 17 feet


Average/520008: if the average of 5 and k is equal to the average of 2,6 and k what is k value
1 solutions

Answer 345901 by Maths68(1474) About Me  on 2011-10-24 01:57:52 (Show Source):
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(5+k) / 2 = (2 + 6 + k)/3
(5+k) / 2 = (8 + k)/3
3(5+k)=2(8+k)
15+3k=16+2k
3k-2k=16-15
k=1


Check
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(5+k) / 2 = (2 + 6 + k)/3
(5+1) / 2 = (2 + 6 + 1)/3
6/2=9/3
3=3


Average/519932: Joe has scores of 94, 71, 89, 73 on his first four exams in his math class. He wants to get a final grade of B for the course. To do this, his exam average must be greater than or equal to 80 and less than 90. he has one exam remaining. What range of scores will give him a final grade of B
Show the answer mathematically.
Write the answer as a statement.
1 solutions

Answer 345899 by Maths68(1474) About Me  on 2011-10-24 01:51:33 (Show Source):
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Let
Socre of fifth exam = x
Avarage for five exams = (97+71+89+73+x)/5 = (324+x)/5
His exam average must be greater than or equal to 80 and less than 90
80≤(324+x)/5<90
Now
For 80≤(324+x)/5
80≤(324+x)/5
Multiply by 5
5*80≤5*(324+x)/5
400≤(324+x)
400-324≤x
76≤x
For
(324+x)/5<90
Multiply by 5
5*(324+x)/5<90*5
324+x<450
x<450-324
x<126
Range of x
76≤x<126
Range of marks is between 76 and 125
He must score marks between 76 and 125 in his fifth test to maintain an average which will give him a grade B.
If the total marks of an exam is 100 then range must be between 76 and 100.


Travel_Word_Problems/519942: If I rode my bike 24 mile is 70 minutes, how many miles was I riding per hour?
1 solutions

Answer 345897 by Maths68(1474) About Me  on 2011-10-24 00:55:39 (Show Source):
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Change the minutes into hour
70 minutes = 70 * (1/60) hours
70 minutes = 7/6 hours
70 minutes = 1.17 hours
Speed = Distance / time = 24/1.17 = 20.51 mph


Money_Word_Problems/519963: ralph chase plans to sell a piece of property for $180,000. He wants the money to be paid off in two ways- a short term note at 9% interest and a long term at 7% interest. find the amount of each note if the total annual interest paid is $14,600.
1 solutions

Answer 345896 by Maths68(1474) About Me  on 2011-10-24 00:47:03 (Show Source):
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Total Amount = $180,000
Total Interest = $14,600
Amount to be paid off at 9% = x
Amount to be paid off at 7% = 180,000 - x
Amount to be paid off at 9% * 9% + Amount to be paid off at 7% * 7% = Total Interest
x*9/100 + (180000-x)*7/100=14600
x*0.09+(180000-x)*0.07=14600
0.09x+12600-0.07x=14600
0.02x=14600-12600
0.02x=2000
x=2000/0.02
x=100,000

Amount to be paid off at 9% = x = $100,000
Amount to be paid off at 7% = 180,000 - 100,000 = $80,000

Check
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100000 * 0.09 + 80000 * 0.07 = 14600
9000+5600=14600
14600=14600