q: The probability is 1/2 that a certain coin will turn up heads on any given toss. If the coin is to be tossed three times, what is the probability that on at least one of the tosses the coin will turn up tails?
Options:
(A) 1/8
(B) 1/2
(C) 3/4
(D) 7/8
(E) 15/16
a: P(at last 1 tails) = 1 - P(all heads) = 1 - (1/2)^3 = 7/8. The answer is (D).
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q: A can do a piece of work in 3 hours; B and C together can do it in 2 hours, which A and B together can do it in 2 hours. How long will C alone take to do it?
Options:
(A) 2hours
(B) 5hours
(C) 6hours
(D) 4hours
(E) 3hours
a: A's 1 hour work = 1/3;
(B + C)'s 1 hour work = 1/2;
(A + B)'s 1 hour work = 1/2
(A + B + C)'s 1 hour work = (1/3 + 1/2) = 5/6
C's 1 hour work = (5/6 - 1/2) = 1/3
C alone will take 3 hours to do the work. The answer is (E).
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q: Find the amount on Rs.8000 in 9 months at 20% per annum, if the interest being compounded quarterly?
Options:
(A) 9261
(B) 1261
(C) 9621
(D) 9162
(E) 5000
a: A = 8000(21/20)3 = 9261 The answer is (A).
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q: Which of the following is a prime number ?
Options:
(A) 90
(B) 94
(C) 96
(D) 97
(E) 98
a:
Clearly, 97 is a prime number. The answer is (D).
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