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edjones answered: 7568 problems
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Rate-of-work-word-problems/248813: A farmer working together with his son needs 3 hours to plow a field. The farmer working alone can plow the field in 4 hours. How long would it take the son working alone to plow the field?
I need the rate of work (R), the time of work (T) , and the work done (W)
the equation is RT = W.
It would help if I am provided a detailed explanation
1 solutions

Answer 181290 by edjones(7569) About Me  on 2009-12-11 19:04:53 (Show Source):
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Farmer does 1/4 the job in 1 hour.
Both do 1/3 the job in 1 hr.
Let the son do 1/x the job in 1 hr.
.
1/4 + 1/x = 1/3
3x+12=4x multiply each side by 12x (LCM) to eliminate fractions.
x=12 hrs it takes the son to do the job alone.
.
Ed


Coordinate-system/248805: what is the slope y=-5/2x-5
1 solutions

Answer 181287 by edjones(7569) About Me  on 2009-12-11 18:51:53 (Show Source):
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y=mx + b the slope=m
y=-5/2x - 5
m=-5/2
.
Ed


Sequences-and-series/248800: I have a problem with sequence and series and I do not understand how to solve it. The questions is -6, 18, -54
1 solutions

Answer 181285 by edjones(7569) About Me  on 2009-12-11 18:38:15 (Show Source):
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18/-6 = -3
-54/18= -3
r=-3
This is a geometric sequence.
The next number in the sequence is -54*-3=162
.
Ed


logarithm/248760: I need the steps for entering 4+2log(5)/1-log(5) using a TI30xa.
The answer is 17.932, but I cannot come up with it using the calculator.
Thanks.
1 solutions

Answer 181242 by edjones(7569) About Me  on 2009-12-11 15:59:43 (Show Source):
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Use parentheses properly and you will get the answer.


Probability-and-statistics/248757: I have a probability question....
10 percent of a yield is defective
the yield is 10
what is the probability that 5 will be defective?
1 solutions

Answer 181241 by edjones(7569) About Me  on 2009-12-11 15:41:20 (Show Source):
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Let x be defective and y be sound.
x=.1 y=.9
nCr = 10C5 = 252 coefficient of the squared binomial.
252x^5y^5 the 6th term of (x+y)^10
= 252*.1^5*.9^5
=.001488...
.
Ed


Probability-and-statistics/248695: Amy and Martin play a game in which they take turns flipping a fair coin until one of them flips a head. The first person to flip a head is the winner. If Amy goes first, find the probability that she wins.
1 solutions

Answer 181240 by edjones(7569) About Me  on 2009-12-11 15:28:13 (Show Source):
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Chances of winning on that flip before the game begins.
A==M
1/2 1/4
1/8 1/16
1/32 1/64
.
1/8 / 1/2 = 1/4
1/32 / 1/8 = 1/4
This is an infinite geometric sequence.
r=1/4=.25
S=a%5B1%5D%2F%281-r%29=.5%2F%281-.25%29=.5%2F.75=2%2F3 Amy's probability of winning.
.
Ed


Probability-and-statistics/248725: There are 5 pairs of socks in a drawer. 2 Blue pairs, 2 Black pairs and one gray pair. The socks are not folded together. If you randomly pick two socks, what is the probability that you will pick a matched pair? that you will pick a gray pair?
1 solutions

Answer 181236 by edjones(7569) About Me  on 2009-12-11 14:57:14 (Show Source):
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nCr=n!/((n-r)!r!)
There are 10 socks.
.
Pick a gray pair:
2C2 / 10C2 = 1/45
.
4C2 / 10C2 = 6/45 blue pair or black pair
.
Any pair: 6/45 + 6/45 + 1/45
=13/45
.
Ed


Numeric_Fractions/248741: i have a multiple fractions equation & need to know how to calculate it (i am online with my ps3 so i cannot type it in a normal manner i'll use a / to represent the fraction) the problem is 2/3 - 5/9 + 5/6 = ? these three fractions together are confusing me terribly because i don't know where to start at
1 solutions

Answer 181234 by edjones(7569) About Me  on 2009-12-11 14:30:17 (Show Source):
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2/3 - 5/9 + 5/6
=12/18 - 10/18 + 15/18 Find the LCD and the rest is simple.
=17/18
.
Ed


logarithm/248732: Solve the equation and express the solution in exact form:
4%5E%283x%29+=+1%2F64
1 solutions

Answer 181233 by edjones(7569) About Me  on 2009-12-11 14:26:04 (Show Source):
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4^(3x) = 1/64
log[4](4^(3x)=log[4](1/64)
3x=-3
x=-1
.
Ed


real-numbers/248746: The below line can represent what solution set. Select the best answer:
a. All integers less than 5
b. All real numbers greater than 0
c. All counting numbers less than 6
d. All irrational numbers between 1 and 5
______________________
1 2 3 4 5
1 solutions

Answer 181232 by edjones(7569) About Me  on 2009-12-11 14:21:27 (Show Source):


Inequalities/248735: If x>13, find 7x + 2
1 solutions

Answer 181231 by edjones(7569) About Me  on 2009-12-11 14:19:44 (Show Source):
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If x>13, find 7x + 2
7*13 + 2 > 93
.
Ed


Probability-and-statistics/248742: What is the probability of a randomly selected day of the week starting with the letter S?
1 solutions

Answer 181230 by edjones(7569) About Me  on 2009-12-11 14:15:39 (Show Source):


Probability-and-statistics/248737: Suppose 39 newly created pairs of jeans are placed in a bin to be checked for quality. Of these, 4 will not be of high enough quality to sell. Suppose that two pairs of jeans are randomly selected, without replacement, from the bin. What is the chance that both pairs of jeans selected will be substandard? Please help me with this problem. Thanks!
1 solutions

Answer 181229 by edjones(7569) About Me  on 2009-12-11 14:13:35 (Show Source):
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nCr=n!/((n-r)!r!) Combination of n things taken r at a time.
.
4C2/39C2=6/741 chance of 2 substandard pair being selected.
.
Ed


Miscellaneous_Word_Problems/248705: Alice, Beth, and Carlie have ten identical red balloons. In how many ways can the girls split up the balloons such that each of them gets at least one red balloon?
1 solutions

Answer 181228 by edjones(7569) About Me  on 2009-12-11 14:01:03 (Show Source):
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This is the same as a 7 balloon problem where girl(s) can get none.
The answer is 36. I worked it out on paper but couldn't figure out a formula.
.
Ed


Quadratic_Equations/248717: Indicate the axis of symmetry of the parabola
y = x^2 + 8x + 20
1 solutions

Answer 181226 by edjones(7569) About Me  on 2009-12-11 13:23:43 (Show Source):
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y=x^2 + 8x + 20
axis of symmetry = -b/2a = -8/2 = -4
.
Ed


Proportions/248718: The theoretical probability of undesirable side effects resulting from taking Pyrene is 1 in 15. If 180 people take Pyrene to relieve congestion, theoretically how many will encounter undesirable side effects?
1 solutions

Answer 181225 by edjones(7569) About Me  on 2009-12-11 13:19:37 (Show Source):
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x/180 = 1/15
x=180/15
=12
.
Ed


Sequences-and-series/248545: Find the sum 1+ 1/2+1/4+...+1/1024
an=1+(n-1) ^ -1/2
1 solutions

Answer 181153 by edjones(7569) About Me  on 2009-12-10 23:17:08 (Show Source):
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(1/2)/1=1/2
(1/4)/(1/2)=1/2
r=1/2 Geometric sequence.
a%5Bn%5D=a%5B1%5Dr%5E%28n-1%29
(1/2)^(n-1)=1/1024
log[1/2]((1/2)^n-1)=log[1/2](1/1024) Finding n
n-1=10
n=11
S%5B11%5D=a%5B1%5D%28%281-r%5En%29%2F%281-r%29%29 Sum of a finite geometric sequence.
=1%28%281-%281%2F2%29%5E11%29%2F%281-%281%2F2%29%29%29
=.9995/.5
=1.999... the sum


Probability-and-statistics/248546: a bag has 2 red martbles 3 green marbles and 1 blue marble. if you randomly take out 2 marbles at once whats the probability of getting a blue and a green marble?
1 solutions

Answer 181145 by edjones(7569) About Me  on 2009-12-10 22:08:47 (Show Source):
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nCr=n!/((n-r)r!) Combination of n things taken r at a time.
.
2C6=15 all marbles
.
1C1=1 blue
3C1=3 green
2C0=1 red
.
(1*3*1)/15= 1/5 probability of getting a blue and a green.
.
Ed


Linear_Equations_And_Systems_Word_Problems/248544: In a room with 35 men, 80% of the occupants are women. How many women are in the room?
1 solutions

Answer 181142 by edjones(7569) About Me  on 2009-12-10 21:52:52 (Show Source):
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Let x=everyone in the room.
100-80=20 % of occupants in the room that are male.
.2x=35
x=35/.2
x=175
175-35=140 women in the room.
.
Ed


Numbers_Word_Problems/248402: use the difference of two squares theorem to find all of the solutions to the following equations: x^2=81
1 solutions

Answer 181036 by edjones(7569) About Me  on 2009-12-10 18:38:34 (Show Source):
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x^2=81
x^2-81=0
(x-9)(x+9)=0
x=9, x=-9
.
Ed


Polygons/248418: How do you find the measure of an interior angle and an exterior angle given the number of sides of each regular polygon? and we have to round to the nearest Tenth if necessary.
14. 8
15. 9
16. 13
1 solutions

Answer 181034 by edjones(7569) About Me  on 2009-12-10 18:34:23 (Show Source):
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n=number of sides.
Int angle=(n-2)* 180/n degrees.
ext angle=360/n
.
14. n=8
6* 180/8 =135 deg int angle
360/8=45 deg ext angle.
.
Ed


Linear-systems/248400: how do you put this math question in standard form y=6/7x+3
1 solutions

Answer 181025 by edjones(7569) About Me  on 2009-12-10 18:13:39 (Show Source):
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Standard form: Ax+By=C (A, B and C are integers.)
y=6/7x+3
7y=6x+21 Multiply each side by 7.
6x-7y=-21
.
Ed


Equations/248372: A bottle filled with water weighs 9.6 kg. If the water by itself weighs 5 times as much as the bottle, What is the weight of the bottle?
1 solutions

Answer 181013 by edjones(7569) About Me  on 2009-12-10 17:41:40 (Show Source):
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Let x=weight of the bottle
5x+x=9.6
6x=9.6
x=1.6 kg
.
Ed


Exponents/248379: can 8 to the 4th power times 8 to the 7th power be simplified?

1 solutions

Answer 181007 by edjones(7569) About Me  on 2009-12-10 17:33:26 (Show Source):
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8^4 * 8^7 = 8^11


Travel_Word_Problems/248271: if someone is traveling to a meeting 60 miles away at 30 per hour how many hours will it take to get there?
1 solutions

Answer 181004 by edjones(7569) About Me  on 2009-12-10 17:31:47 (Show Source):


logarithm/248298: log2^x+log2^4=3
1 solutions

Answer 180992 by edjones(7569) About Me  on 2009-12-10 17:07:30 (Show Source):
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log2^x+log2^4=3
10^(log2^x)10^(log2^4)=10^3
2^x*2^4=10^3
2^x=1000/16
log[2](2^x)=log[2](62.5)
x=5.966
.
Ed


Polynomials-and-rational-expressions/248334: what are all the real zeros of f(x)=x^4-5x^2+4 ? and can you please show me how to work this problem out step by step ?
1 solutions

Answer 180988 by edjones(7569) About Me  on 2009-12-10 16:53:37 (Show Source):
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x^4-5x^2+4=0 This is a quadratic
(x^2-4)(x^2-1)=0
(x+2)(x-2)(x+1)(x-1)=0
x=2, x=-2, x=1, x=-1 The zeros.
.
Ed


Trigonometry-basics/248291: F(x)= x^3 - 6x2 +13x - 10
Find all the zeros of the function
thx!
1 solutions

Answer 180977 by edjones(7569) About Me  on 2009-12-10 16:39:34 (Show Source):
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x^3 - 6x2 +13x - 10=0
do the rational roots test by dividing +- a/d = +- 10/1
The possible rational factors are +- 10, 5, 2, 1
testing these we find that 2 is a zero.
next we divide x^3 - 6x2 +13x - 10 by x-2 and get x^2-4x+5 which is a quadratic.
x^2-4x+5=0
x^2-4x =-5
x^2-4x+4=-5+4 completing the square.
(x-2)^2=-1
x-2=+-sqrt(-1)
x=2+i, x=2-i the other 2 zeros.
.
Ed


Numbers_Word_Problems/248309: When the reciprocal of three times a number is subtracted from the reciprocal of the number, the result is one-sixth. Find the number.
1 solutions

Answer 180960 by edjones(7569) About Me  on 2009-12-10 15:31:15 (Show Source):
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Let x be the number.
1/x - 1/3x = 1/6
6-2=x
x=4
.
Ed


Graphs/248046: Please help me solve and graph this equation:72<9r
1 solutions

Answer 180867 by edjones(7569) About Me  on 2009-12-10 01:24:43 (Show Source):
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r>8 divide each side by 9.


Numbers_Word_Problems/248101: Find a sequence of three intergers with a common difference of three, such that three times the sum of the first two intergers minus five times the largest interger is 61.
1 solutions

Answer 180865 by edjones(7569) About Me  on 2009-12-10 01:19:02 (Show Source):
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Let the integers be x, x+3, x+6
.
3(x+x+3)-5(x+6)=61
6x+9-5x-30=61
x-21=61
x=82
.
Ed