## Solution
1/15 + 1/30 - 1/40 = 9/120
120/9 = 13 3/7
## What the question and answer could be
Two pipes A and B can fill a cistern in 15 and 30 minutes respectively, and a third pipe C can empty it in 40 minutes. How long will it take to fill the cistern if all the three are opened at the same time?
Options:
(A) 17 1/4 min
(B) 28 1/7 min
(C) 17 1/7 min
(D) 13 3/7 min
(E) 17 5/7 min
(D)

## Solution
The prompt is essentially asking for the maximum number of 4x 4 squares that can be cut from a larger 16 by 16 square. Since each 'row' and each 'column' of the larger square can be sub-divided into 4 'pieces' each, we have (4)(4) = 16 total smaller squares (at maximum).
## What the question and answer could be
What is the maximum number of pieces of birthday cake of size 4" by 4" that can be cut from a cake 16" by 16"?
Options:
(A) 5
(B) 4
(C) 16
(D) 20
(E) 25
(C)

## Solution
Distance between Bob's house and Jamie's restaurant: 30 x 3 = 90 km
Rate of speed to get to Bob's house in an hour: 90 x 1 = 90 km/h
Rate of speed to get to Bob's house in half an hour: 90/2 = 45 km/h
## What the question and answer could be
Jamie's friend Bob is having a party, but Jamie forgot and went to dinner with her friend Emily instead. Bob's party starts in half an hour. Bob lives 30 km away from Jamie, and the restaurant Jamie and Emily are at is three times as far away from Bob's house as Jamie's house is.
How fast would Jamie have to drive in order to get to Bob's party on time?
Options:
(A) 30 km/h
(B) 45 km/h
(C) 60 km/h
(D) 75 km/h
(E) 90 km/h
(B)

## Solution
7/8 * 6/7 = 3/4
1-(3/4) = 1/4
## What the question and answer could be
A shipment of 8 TV sets contains 1 black and white sets and 7 color sets. If 2 TV sets are to be chosen at random from this shipment, what is the probability that at least 1 of the 2 sets chosen will be a black and white set?
Options:
(A) 1/7
(B) 1/4
(C) 5/14
(D) 11/28
(E) 13/28
(B)