If 10 litres of an oil of Rs.50 per litres be mixed with 5 litres of another oil of Rs.68 per litre then what is the rate of mixed oil per litre?
Options:
(A) Rs.49.17
(B) Rs.51.03
(C) Rs.56
(D) Rs.55.33
(E) None of the above

50*10 = 500
68*5 = 340
840/15 = 56 So the answer is: (C).

Three pipes A, B and C can fill a tank from empty to full in 30 minutes, 20 minutes and 10 minutes respectively. When the tank is empty, all the three pipes are opened. A, B and C discharge chemical solutions P, Q and R respectively. What is the proportion of solution P in the liquid in the tank after 3 minutes?
Options:
(A) 3/11
(B) 2/11
(C) 1/11
(D) 4/11
(E) 1/11

Part filled by (A + B + C) in 3 minutes = 3(1/30 + 1/20 + 1/10) = 11/20
Part filled by A in 3 minutes = 3/30
Required ratio = 3/30 * 20/11 = 2/11 So the answer is: (B).

Which of the following is a prime number ?
Options:
(A) 27
(B) 45
(C) 97
(D) 98
(E) 100

Clearly, 97 is a prime number. So the answer is: (C).

An analyst will recommend a combination of 1 industrial stocks, 1 transportation stocks, and 1 utility stocks. If the analyst can choose from 5 industrial stocks, 4 transportation stocks, and 3 utility stocks, how many different combinations of 3 stocks are possible?
Options:
(A) 12
(B) 19
(C) 60
(D) 180
(E) 720
5C1 * 4C1 * 3C1 = 5*4*3 = 60. So the answer is: (C).