q: X can finish a work in 20 days. Y can finish the same work in 16 days. Y worked for 12 days and left the job. how many days does X alone need to finish the remaining work?
Options:
(A) 2
(B) 3
(C) 9
(D) 5
(E) 8
a: Stream of consciousness: Work done by X in 1 day = 1/20
Work done by Y in 1 day = 1/16
Work done by Y in 12 days = 12/16 = 3/4
Remaining work = 1 3/4 = 1/4
Number of days in which X can finish the remaining work = (1/4) / (1/20) = 5 The answer is (D).

question: What amount does Kiran get if he invests Rs. 18000 at 15% p.a. simple interest for four years?
Options:
(A) 3888
(B) 26989
(C) 26700
(D) 28800
(E) 2879
answer: Stream of consciousness: Simple interest = (18000 * 4 * 15)/100 = Rs. 10800
Amount = P + I = 18000 + 10800 = Rs. 28800 The answer is (D).

q: What percent is 36 paisa's of 12 rupees?
Options:
(A) 3 %
(B) 4 %
(C) 5 %
(D) 6 %
(E) 7 %
a: Stream of consciousness: 12 Rupees = 1200paisa's
36/1200 100 = 3/12
12/3 = 3 % The answer is (A).

question: A train is running at a speed of 40 km/hr and it crosses a post in 18 seconds. What is the length of the train?
Options:
(A) 190 metres
(B) 160 metres
(C) 180 metres
(D) 120 metres
(E) 200 metres
answer: Stream of consciousness: Speed of the train, v = 40 km/hr = 40000/3600 m/s = 400/36 m/s
Time taken to cross, t = 18 s
Distance Covered, d = vt = (400/36) 18 = 200 m
Distance covered is equal to the length of the train = 200 m The answer is (E).

q: At what rate percent on simple interest will a sum of money double itself in 30 years?
Options:
(A) 3 1/3%
(B) 3 1/6%
(C) 3 1/5%
(D) 3 5/3%
(E) 7 1/3%
a: Stream of consciousness: P = (P*30*R)/100
R = 3 1/3% The answer is (A).

q: The average age of a class of 42 students is 16 yrs. if the teacher's age is also included, the average increases by one year. Find the age of the teacher
Options:
(A) 30 Years
(B) 31 Years
(C) 32 Years
(D) 34 Years
(E) 59 Years
a:
Stream of consciousness: Total age of students is 42X16 = 672 Years
Total age inclusive of teacher = 43X (16+1) = 731
So, Teacher's age is 731-672 = 59 Yrs
There is a shortcut for these type of problems
Teacher's age is 16+(43X1) = 59 Years The answer is (E).