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: 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).
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q: Count the two-digit whole numbers which yield a remainder of 5 when divided by 10 and also yield a remainder of 0 when divided by 3?
Options:
(A) Two
(B) Five
(C) Three
(D) One
(E) Six
a: Stream of consciousness: Answer = C) Three
Two digit Numbers giving remainder 5 when divided by 10 = 15, 25, 35, 45, 55, 65, 75, 85, 95
The numbers giving remainder 0 when divided by 3 = 15, 45, 75 = 3 The answer is (C).
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q: Two pipes can fill a tank in 20 and 24 minutes respectively and a waste pipe can empty 3 gallons per minute. All the three pipes working together can fill the tank in 15 minutes. The capacity of the tank is?
Options:
(A) 820 gallons
(B) 128 gallons
(C) 120 gallons
(D) 129 gallons
(E) 220 gallons
a:
Stream of consciousness: Work done by the waste pipe in 1 minute = 1/15 - (1/20 + 1/24) = - 1/40
Volume of 1/40 part = 3 gallonsVolume of whole = 3 * 40 = 120 gallons. The answer is (C).
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