Search found 92 matches
Total number of ways of choosing 2 balls is 8C2 = 8!/6!2! = 28 Prob of picking a white ball first time = 3/8 Prob of picking a white ball second time (having not picked it first time) = 5/8 * 3/7 = 15/56 Total prob of picking at least one white ball = 3/8 + 15/56 = (21+15)/56 = 36/56 = 18/28 Number ...
- by moutar
Wed Apr 22, 2009 11:15 am- Forum: Problem Solving
- Topic: Another Permutation
- Replies: 3
- Views: 1282
I differentiated to check. Obviously it can be done by logic. I'll write both. Differentiating: Max when dP/dS = 0 dP/dS = 2(S-4) (by the chain rule) 2(S-4) = 0 when S = 4 Logic: As it says (S-4)^2 is always positive (or 0). So -2(S-4)^2 is always negative and will take passengers away from the 32. ...
- by moutar
Wed Apr 22, 2009 10:58 am- Forum: Problem Solving
- Topic: MGMAT cat 6B PS
- Replies: 2
- Views: 1063
Let the perfect square be denoted: S=a^x+b^y+c^z. x y and z must all be even for S to be a perfect square. Possible values of x are 0, 2, 4 (Total 3) Possible values of y are 0, 2 (Total 2) Possible values of z are 0, 2, 4, 6 (total 4) So total possible factors = 3*2*4 = 24 I actually disagree with ...
- by moutar
Wed Apr 22, 2009 10:45 am- Forum: Problem Solving
- Topic: a, b, c > 2
- Replies: 6
- Views: 1554
Choose values of x and y such that 3x + 7y is a multiple of 11. x = 5, y = 1 works Plug each of these into the answers and you'll find that: 1. 4x + 6y = 20 + 6 = 26 WRONG 2. x + y + 4 = 5 + 1 + 4 = 10 WRONG 3. 9x + 4y = 45 + 4 = 49 WRONG 4. 4x - 9y = 20 - 9 = 11 5. 7x + 4y = 35 + 4 = 39 WRONG There...
- by moutar
Mon Apr 20, 2009 11:05 am- Forum: Problem Solving
- Topic: multiple
- Replies: 5
- Views: 1480
a + b + c = 100
As said above one of the prime number needs to be 2.
2 + b + c = 100
b + c = 98 ... (1)
We know the difference between b and c is 36.
c - b = 36 ... (2)
(1) - (2) ... 2b = 62 => b = 31
c = 36 + 31 = 67 - Answer: 5
- by moutar
Mon Apr 20, 2009 10:48 am- Forum: Problem Solving
- Topic: prime
- Replies: 3
- Views: 1230
There are 9 different combinations that can happen. Take Jim as the first one and Renee the second.
RR RP RS
PR PP PS
SR SP SS
The combinations RS, PR and SP will give Jim a win so the probability of him winning is 1/3. E.
- by moutar
Sun Apr 19, 2009 5:23 am- Forum: Problem Solving
- Topic: rock, paper and scissors
- Replies: 3
- Views: 1318
- by moutar
Sat Apr 18, 2009 2:02 am- Forum: Problem Solving
- Topic: triangle
- Replies: 1
- Views: 1019
There are 15 other fruits.
Percentage = Difference/Other fruits x 100
= 35-15/15 x 100
= 20/15 x 100
= 133.33%
I don't like the wording of the question. It sort of makes sense but could have been written better. Is this the exact question?
- by moutar
Sat Apr 18, 2009 2:01 am- Forum: Problem Solving
- Topic: apples
- Replies: 2
- Views: 1303
Let t be the number of tomatoes and p be the number of peppers. From the information given we can form 2 simultaneous equations. .75t + .6p = 30 (1) 4t + p = 116 (2) (1) x 20: 15t + 12p = 600 (3) (2) x 12: 48t + 12p = 1392 (4) (4) - (3): 33t = 792 t = 24 t=24 into (2): 4x24 + p = 116 96 + p = 116 p ...
- by moutar
Sat Apr 18, 2009 1:56 am- Forum: Problem Solving
- Topic: peppers
- Replies: 2
- Views: 1454
Let a be the length of the table.
Length of strip: 3 + a + 3 + a = x
6 + 2a = x
Surface area: 3a = x
Equate the x's:
3a = 2a + 6
a = 6
Answer E
- by moutar
Mon Apr 13, 2009 6:43 am- Forum: Problem Solving
- Topic: Perimeter
- Replies: 4
- Views: 2053
- by moutar
Mon Apr 13, 2009 4:48 am- Forum: Problem Solving
- Topic: Easy one!
- Replies: 1
- Views: 1442
- by moutar
Sun Apr 12, 2009 4:16 pm- Forum: Problem Solving
- Topic: range question
- Replies: 2
- Views: 1598
The whole belt is made up of 2 horizontal parts (top and bottom) and 2 round half-circumference parts.
So:
15 = Top + bottom + 2 x half circle
Top = bottom (call this A)
15 = 2A + 2 x pi*d/2 (d=1)
15 = 2A + pi
15 - pi = 2A
A = (15 - pi)/2
- by moutar
Sun Apr 12, 2009 3:44 pm- Forum: Problem Solving
- Topic: applied circumference problem..finding distance?
- Replies: 4
- Views: 1439
- by moutar
Sun Apr 12, 2009 3:25 pm- Forum: Problem Solving
- Topic: Voting districts
- Replies: 2
- Views: 1251
angle ABC = 90 degrees (angle subtending a diameter) AB^2 + BC^2 = AC^2 AC = 2, BC = 1 -> AB^2 + 1 = 4 AB^2 = 3 AB = root(3) Area of triangle = 1/2 x base x (perpendicular) height = 1/2 x BC x AB = 1/2 x 1 x root(3) = root(3)/2 B.
- by moutar
Sun Apr 12, 2009 3:14 pm- Forum: Problem Solving
- Topic: inscribed or circumscribed
- Replies: 3
- Views: 1268