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edjones answered: 7568 problems
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1 solutions
Answer 202120 by edjones(7569)   on 2010-03-05 19:55:23 (Show Source):
You can put this solution on YOUR website!Let s=hrs sammy takes and m=hrs martin takes
s=m+5
in 1 hr martin gets 1/m of the job done and sammy gets 1/(m+5) done.
1/m + 1/(m+5) = 1/6
6(m+5)+6m=m(m+5)
6m+30+6m=m^2+5m
m^2-7m-30=0
(m-10)(m+3)=0
m=10 hrs
s=15 hrs
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Ed
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Probability-and-statistics/277427: A man is to play a game as follows. In three tosses of balanced coin, he will get a reward of RS. 20,000,RS.10,000 ,RS. 5,000 and no reward if he gets 3 tails, 2 tails, 1 tail and no tail respectively. whats is his expected return. If the entrance fee for contest is Rs. 7,000 will he play the game?
1 solutions
Answer 201970 by edjones(7569) on 2010-03-04 23:47:24 (Show Source):
You can put this solution on YOUR website!(t+h)^3=
t^3=.5^3=1/8
3t^2h=3*.5^2*.5=3/8
3th^2=3/8
h^3=1/8
.
In 8 tries he spends 7000*8=56000
and wins
20000 all tails
30000 2 tails
15000 one tail
------add
65000
.
65000-56000=9000 is the expected return after 8 tries
.
9000/8=RS 1125 expected return per try.
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Ed
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test/276964: Exactly how many degrees are there between the hands of a clock at 3:40 pm
1 solutions
Answer 201776 by edjones(7569) on 2010-03-04 02:20:04 (Show Source):
You can put this solution on YOUR website!The hr hand is 2/3 the way to the 4 or 11/36 around the clock.
11/36 * 360 = 110 deg
The minute hand is 8/12 around the clock.
8/12 * 360 = 240 deg
.
240-110=130 degrees between the hands.
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Ed
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Equations/276975: Can you pleas help me with this equation.
Solve using the addition and multiplication principles.
5/6(5x-2)-2/3 ≥ 11/6
1 solutions
Answer 201771 by edjones(7569) on 2010-03-04 01:53:06 (Show Source):
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Equations/277023: I do not understand the steps in a few fractional equation problems, but I would like to know how to work this one out, so I wont be confused in the future. n - 16/n = 96/5
1 solutions
Answer 201761 by edjones(7569) on 2010-03-04 01:18:41 (Show Source):
You can put this solution on YOUR website!n - 16/n = 96/5
5n^2-80=96n multiply each side by 5n (LCM)
5n^2-96n-80=0
5n^2+4n-100n-80=0
n(5n+4)-20(5n+4)=0 factoring by grouping.
(n-20)(5n+4)=0
5n=-4, n=-4/5
n=20
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Ed
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Equations/277025: How could I solve this equation dealing with fractions.
x/x+4 - 2 = 12/x-12
1 solutions
Answer 201759 by edjones(7569) on 2010-03-04 01:09:36 (Show Source):
You can put this solution on YOUR website!x/(x+4) - 2 = 12/(x-12)
x(x-12)-2(x+4)(x-12)=12(x+4) multiply each side by (x+4)(x-12) (LCM)
x^2-12x-2(x^2-8x-48)=12x+48
x^2-12x-2x^2+16x+96=12x+48
x^2+8x-48=0 subtract the left side from the right
(x-4)(x+12)=0
x=4, x=-12
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Ed
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Permutations/276988: In how many different ways can a panel of 12 jurors and 2 alternates be chosen from a group of 20 prospective jurors?
1 solutions
Answer 201747 by edjones(7569) on 2010-03-03 23:29:21 (Show Source):
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Permutations/276980: In how many ways can 10 letters: 2 C’s, 3 D’s, and 5 F’s be awarded to 10 politicians, one letter for each politician?
1 solutions
Answer 201745 by edjones(7569) on 2010-03-03 23:21:57 (Show Source):
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Permutations/276981: A survey of 51 pet owners revealed that 32 owned dogs, 38 owned cats, and 3 owned neither dogs nor cats. How many owned both dogs and cats?
1 solutions
Answer 201744 by edjones(7569) on 2010-03-03 23:14:20 (Show Source):
You can put this solution on YOUR website!51-3=48 own cars or dogs or both. Make a Venn diagram and put 3 in the rectangle but out side the circles.
Let x= owned both dogs and cats. That is the intersection of the 2 circles.
32-x+38-x+x=48 the union of the 2 circles IE everything in the circles.
32-x+38-x+x=48
70-x=48
-x=-22
x=22 owned both dogs and cats.
FYI: 10 goes to the left of the intersection and 16 to the right.
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Ed
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test/276966: the time allowed for completing a certain piece of work is 40 days. By extending the time by 10 days we find that 25 fewer man will be needed. How many men are required to finish the work in 40 days?
1 solutions
Answer 201743 by edjones(7569) on 2010-03-03 22:53:34 (Show Source):
You can put this solution on YOUR website!Let x=number of men needed to finish job in 40 days
40 * x = 40x man-days required
50 * x-25 = 50(x-25) man-days
40x=50(x-25)
40x=50x-1250
-10x=-1250
x=125 number of men needed to finish job in 40 days.
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Ed
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Permutations/276952: Fifteen dogs enter a Goofy Dog contest. In how many different ways can a champion, a first runner-up, and a second runner-up be selected?
1 solutions
Answer 201738 by edjones(7569) on 2010-03-03 22:29:18 (Show Source):
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Rectangles/276401: When the length of each side of a square is increased by 5 inches, the area of the resulting square is 2.25 times the area of the original square. What is the area of the original square?
1 solutions
Answer 201443 by edjones(7569) on 2010-03-02 22:30:40 (Show Source):
You can put this solution on YOUR website!Let s=original side
A=s^2
.
(s+5)^2=2.25s^2
s^2+10s+25=2.25s^2
1.25s^2-10s-25=0 subtract the left side from the right.
s^2-8s-20=0 divide each side by 1.25
(s+2)(s-10)=0
s=10
10^2=100 sq in. area of the original square.
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Ed
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Probability-and-statistics/276406: Given that P(A or B) = 1/3, P(A) = 1/6, and P(A and B) = 1/8, find P(B).
7/24 is the answer but I would really love to know why. This question is worded in a very confusing manner.
1 solutions
Answer 201440 by edjones(7569) on 2010-03-02 22:13:23 (Show Source):
You can put this solution on YOUR website!Become familiar with Venn diagrams and this will become much simpler.
In the intersection of the 2 circles put 1/8.
1/6 - 1/8 = 1/24 put this in the semicircle to left of 1/8
1/3 is the union of the 2 circles.
1/24 + 1/8 + x = 1/3
x=1/6 put this in the semicircle right of 1/8
1/8 + 1/6 = 7/24 P(B)
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Ed
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Probability-and-statistics/276399: You are taking a multiple-choice test that has 12 questions. Each of the questions has 5 choices, with one correct choice per question. If you select one of these options per question and leave nothing blank, in how many ways can you answer the questions?
The answer is 244,140,625 but why?
1 solutions
Answer 201437 by edjones(7569) on 2010-03-02 21:50:45 (Show Source):
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