If the average (arithmetic mean) of the four numbers K, 3K + 3, 3K 4 and 5K + 1 is 60, what is the value of K?
Options:
(A) 11
(B) 15 3/4
(C) 20
(D) 23
(E) 25 3/10
Answer and stream of consciousness: (C)
Stream of consciousness: K + 3K +3 + 3K - 4 + 5K +1 = 12K
(12K)/4 = 60
12K = 60 * 4 = 240
K = 240/ 12 = 20.

A 200 meter long train crosses a man standing on the platform in 9 sec. What is the speed of the train?
Options:
(A) 228
(B) 108
(C) 1266
(D) 188
(E) 80
Answer and stream of consciousness: (E)
Stream of consciousness: S = 200/9 * 18/5 = 80 kmph

A plane flies 500 miles at a speed of r mph. If the plane flies at a speed of r + 250 miles per hour, it would fly the same distance in 1 hour less. What is the value of r?
Options:
(A) 250 mph
(B) 200 mph
(C) 205 mph
(D) 300 mph
(E) 425 mph
Answer and stream of consciousness: (A)
Stream of consciousness: Equation: 500/r = 500/(r+50) + 1
Plug options into the equation
A fits: 500/250 = 500/(250+250) + 1

An enterprising businessman earns an income of Re 5 on the first day of his business. On every subsequent day, he earns an income which is just thrice of that made on the previous day. On the 10th day of business, he earns an income of:
Options:
(A) 21
(B) 22
(C) 20
(D) 45
(E) 30
Answer and stream of consciousness:
(D)
Stream of consciousness: 2nd day he earns = 3(2 5)
3rd day he earns = 3(3 5)
On 20th day he earns 3(20 -5) = 45 rupees