At 15:00 there were 20 students in the computer lab. At 15:03 and every three minutes after that, 3 students entered the lab. If at 15:10 and every ten minutes after that 9 students left the lab, how many students were in the computer lab at 15:44 ?
Options:
(A) 7
(B) 14
(C) 25
(D) 27
(E) 30
Answer and stream of consciousness: (C)
Stream of consciousness: Initial no of students + 3 * (1 + No of possible 3 minute intervals between 15:03 and 15:44) -
8 *(1 + No of possible 10 minute intervals between 15:10 and 15:44)
20 + 3*14 -8 * 4 = 25

When tossed, a certain coin has equal probability of landing on either side. If the coin is tossed 4 times, what is the probability that it will land twice on heads and twice tails?
Options:
(A) 1/8
(B) 1/4
(C) 1/16
(D) 1/32
(E) 1/2
Answer and stream of consciousness: (C)
Stream of consciousness: Must be twice on heads and twice on tails
1/2*1/2*1/2*1/2 = 1/16

Find the odd man out
25, 49, 81, 121, 144, 169
Options:
(A) 49
(B) 121
(C) 144
(D) 169
(E) 25
Answer and stream of consciousness: (C)
Stream of consciousness: 144 is square of 12 which is even number where as all others are squares of odd numbers.

The average mark obtained by 22 candidates in an examination is 46. The average of the first ten is 55 while the last eleven is 40 .The marks obtained by the 11th candidate is ?
Options:
(A) 22
(B) 0
(C) 19
(D) 18
(E) 16
Answer and stream of consciousness:
(A)
Stream of consciousness: It is clear that 22 x 46 = 10 x 55 + K + 11 x 40 K = 22