If A takes x days to do a work then B takes 2x days to do the same work then with in how many day's A will alone complete this work ?
Options:
(A) 27
(B) 23
(C) 24
(D) 25
(E) 26

1/x+1/2x = 1/18 = > 3/2x = 1/18 = > x = 27 days. Hence, A alone can finish the work in 27 days. So the answer is: (A).

A can do a piece of work in 20 days. B in 15 days A and C in 12 days. In how many days can A finish the work if he is assisted by B on one day and C on the next, alternately?
Options:
(A) 7 days
(B) 8 days
(C) 3 days
(D) 9 days
(E) 2 days

A + B = 1/20 + 1/15 = 7/60
A + C = 1/20 + 1/12 = 8/60
7/60 + 8/60 = 15/60 = 1/4
4 days * 2 = 8 days So the answer is: (B).

A 2015 model car had an average mileage of 38 miles per gallon, when the car wight was 180 kilograms. An upgraded version of the car in 2016 gave a mileage of 43 miles per gallon and the car weight was reduced to 150 kilograms. By approximately what percent did the mileage of the car to the weight of the car improve?
Options:
(A) 28
(B) 43
(C) 36
(D) 19
(E) 37

Initial mileage/weight ratio = 38/180 = 190/900
Revised mileage/weight ratio = 43/150 = 258/900 So the answer is: (C).

If n is an integer, then the least possible value of |33 - 5n| is?
Options:
(A) 0
(B) 1
(C) 2
(D) 3
(E) 4
|33 - 5n| represents the distance between 33 and 5n on the number line. Now, the distance will be minimized when 5n, which is multiple of 5, is closest to 33. Multiple of 5 which is closest to 33 is 35 (for n = 7), so the least distance is 2: |33 - 35| = 2. So the answer is: (C).