Q: A Martian bat flies at 60 yards per second from its nest to a dry lake. When it arrives there, it immediately continues at 45 yards per second to a nearby cave. If the distance between the lake and the cave is half the distance between the nest and the lake, what is the average speed, in yards per second, of the bat during the whole flight?
Options:
(A) 36
(B) 40
(C) 42
(D) 54
(E) 65
A: OK... Stream of consciousness: Distance from nest to lake = d, Speed = 60, Time = d/60
Distance from lake to cave = d/2, Speed = 45, Time = d/90
Average speed = (d + d/2)/(d/60 + d/90) = (3/2)/(1/36) = 54
The answer is (D).

Q: A team of eight entered for a shooting competition. The best marks man scored 82 points. If he had scored 92 points, the average scores for. The team would have been 86. How many points altogether did the team score?
Options:
(A) 662
(B) 678
(C) 652
(D) 642
(E) 721
A: OK... Stream of consciousness: 8 * 86 = 688 10 = 678
The answer is (B).

Q: The average age of a class of 32 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) 34 Years
(B) 37 Years
(C) 49 Years
(D) 51 Years
(E) 57 Years
A: OK... Stream of consciousness: Total age of students is 32X16 = 512 Years
Total age inclusive of teacher = 33X (16+1) = 561
So, Teacher's age is 561-512 = 49 Yrs
There is a shortcut for these type of problems
Teacher's age is 16+(33X1) = 49 Years
The answer is (C).

Q: It is the New Year and Mandy has made a resolution to lose weight this year. She plans to exercise and do yoga. For exercise she plans to workout at the gym and ride her bicycle in the ratio of 2:3 everyday. She will also do yoga in the ratio, yoga:exercise = 2:3. If she rides her bike for 10 minutes, how much time will she spend doing yoga? (rounded to minutes)
Options:
(A) 10 min.
(B) 41 min.
(C) 17 min.
(D) 23 min.
(E) 25 min.
A:
OK... Stream of consciousness: The ratio is 2:3 = gym:ride, so (10)(3/2) = 15 minutes at the gym, and 15 + 10 = 25 minutes exercise, so (2/3)(25) = 17 minutes yoga.
The answer is (C).