Q: From a Group of 10 People, Including George and Nina, 3 people are to be selected at random to work on a certain project. What is the probability that 3 people selected will include George but not Nina
Options:
(A) 5/56
(B) 9/56
(C) 28/120
(D) 21/56
(E) 25/56
A: OK... Stream of consciousness: Number of ways of selecting 3 people out of 10 people = 10C3
In the three members George will always be there in the team. At this step we have vacancy for 2 more members and 9 members are available. Lina cannot be there in the team. So 2 members have to be selected and the number of available members = 9 - Nina = 8
Number of ways to form a 3 member team that includes George and excludes Nina = 8C2
Probability = 8C2/10C3 = 28/120
The answer is (C).

Q: John left home and drove at the rate of 45 mph for 2 hours. He stopped for lunch then drove for another 3 hours at the rate of 45 mph to reach his destination. How many miles did John drive?
Options:
(A) 235 miles.
(B) 245 miles.
(C) 225 miles.
(D) 265 miles.
(E) 275 miles.
A: OK... Stream of consciousness: The total distance D traveled by John is given by
D = 45 * 2 + 3 * 45 = 225 miles.
The answer is (C).

Q: On average, the bottle-nosed dolphin comes up for air once every three minutes; the beluga whale, a close relative, comes up for air on average once every six minutes. The number of times a bottle-nosed dolphin would come up for air in a 24 hour period is approximately what percent greater than the number of times a beluga whale would come up for air in that same period?
Options:
(A) 25%
(B) 50%
(C) 75%
(D) 100%
(E) 150%
A: OK... Stream of consciousness: Dolphin once in 3 min;
Beluga once in 6 min;
So, dolphin comes up 2 times frequently than beluga, which is 150% (6-3)/2*100.
The answer is (E).

Q: In what time a sum of money double itself at 8% per annum simple interest?
Options:
(A) 33 1/8%
(B) 33 1/3%
(C) 33 7/3%
(D) 32 1/3%
(E) 12 1/2%
A:
OK... Stream of consciousness: P = (P*8*R)/100
R = 12 1/2%
The answer is (E).