## Search found 92 matches

#### Another Permutation

###### Problem Solving

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: 891

#### MGMAT cat 6B PS

###### Problem Solving

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: 714

#### a, b, c > 2

###### Problem Solving

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: 1147

#### multiple

###### Problem Solving

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: 1042

#### prime

###### Problem Solving

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: 842

#### rock, paper and scissors

###### Problem Solving

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: 980

#### triangle

###### Problem Solving

I would completely agree with you there.

by moutar

Sat Apr 18, 2009 2:02 am
Forum: Problem Solving
Topic: triangle
Replies: 1
Views: 692

#### apples

###### Problem Solving

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: 937

#### peppers

###### Problem Solving

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: 1049

#### Perimeter

###### Problem Solving

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

by moutar

Mon Apr 13, 2009 6:43 am
Forum: Problem Solving
Topic: Perimeter
Replies: 4
Views: 1638

#### Easy one!

###### Problem Solving

25% = 1/4

45% = 9/20

Let y be the total sales in the USA.

Then x = y*1/4*9/20
= 9y/80

y = 80x/9 E.

by moutar

Mon Apr 13, 2009 4:48 am
Forum: Problem Solving
Topic: Easy one!
Replies: 1
Views: 1109

#### range question

###### Problem Solving

Range = biggest - smallest
= 17 - 4
= 13

D.

by moutar

Sun Apr 12, 2009 4:16 pm
Forum: Problem Solving
Topic: range question
Replies: 2
Views: 1170

#### applied circumference problem..finding distance?

###### Problem Solving

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: 999

#### Voting districts

###### Problem Solving

by moutar

Sun Apr 12, 2009 3:25 pm
Forum: Problem Solving
Topic: Voting districts
Replies: 2
Views: 856

#### inscribed or circumscribed

###### Problem Solving

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: 849