Welcome to Coaching Genie's series-4 of Quantitative Aptitude. The Best free IBPS PO Clerk coaching.
31.Between two book-ends in your study are displayed your six favourite
puzzle books. If you decide to arrange the six books in every possible
combination and moved just one book every minute, how long would it take
you? a)8 hours b)12 hours c)15 hours d)9 hours e) 17 hours
Ans.Clearly, number of ways of arranging 6 books = 6! =6 x 5 x 4 x 3 x 2 x 1 = 720. So, total time taken = 720 minutes = 720/60 hours = 12 hours.
32. Five bells toll respectively at intervals of 5, 6, 8, 9 and 10 seconds.How many times will they toll together in one hour excluding the one at the start ? a)5 b)7 c)8 d)9 e)4
Ans. L.C.M. of 5, 6 ,8, 9 and 10 is 360. So, the bells will toll together after every 360 seconds i.e. 6
minutes. Now, 6 x 10= 60 and 6 x 11 = 66.Thus, in 1 hour (or 60
minutes), the bells will toll together 9 times, excluding the one at the
start.
33. Shyam has deposited Rs 2500 in the bank for 2 years at compount interest at the rate of 14% p.a compounded half-yearly. How much amount will he get at the end of 2 years approximately? a)6277 b)4277 c)2277 d)3277 e)5277
Ans. Money is said to be lend at compound interest (C.I) if interest is not paid as soon as falls due, but is added to the principal after a fixed period, so that the amount at the end of period becomes the principal for the next period. If A is the amount , C.I is the compound interest , P is the principal, R is the rate, and t is the time taken then A = P (1 + R/100)t C.I = P[(1 + R/100)t -1] Note 1. If interest is paid half yearly, time is doubled and rate is halved. 2.Compount interest for 1 year is equal to simple interest for 1 year. so here P = 2500 , t = 2 , R = 14% Amount at the end of 2 years at 14% p.a componded half yearly = Since half yearly new t = 2*2 = 4 and new R = 14/2 = 7 A = P (1 + R/100)t = 2500 ( 1 + 7/100)4 = 2500 ( 1 + .07)4 = 2500 * 1.074 =2500 * 1.3108 = 3276.99 => 3277
34. If 25% of a number is 200. What percentage of 200 is the number? a)600% b)500% c)400% d)300% e)200%
Ans. Let the nunber be X. 25/100 * X = 200 so X = 800 Now 800/200 * 100 = 400%
35. Twenty men can build a 40-meter long wall in 30 days. In how many days can fifty men build a 60-meter long wall? a)12 days b)8 days c)10 days d)18 days e)16 days
Ans . m1d1/w1 = m2d2/w2 m, d, and w represent the number of men, the number of days and the volume of work respectively. 20*30/40 = 50*d2/60 =>d2 = 18 days
36. The least number by which 2028 should be multiplied to make it a perfect square is ______ a)13 b)3 c)2 d)4 e)6
Ans. 2|2028 *--------- 2 |1014 *--------- 3 |507 *--------- 13|169 *--------- 13 so 2028 = (2)2 x 3 x (13)2 so the least number by which 2028 must be multiplied such that we get a perfect square is 3. 2028x 3 = 6084 = (78)2
38. A started a business investing Rs.52500 and B joined later with an investment of Rs.22500. In what ratio should the profit be distributed? a)7:4 b)7:3 c)3:4 d)4:7 e)4:6
Ans. Ratio of investments of A and B = Rs.52500 : Rs 22500 =(52500/22500) = 7/3 = 7:3
39. A trader spends 40% of his capital as salary to the staff and 30% of the capital for purchase of commodities. If the cash in hand is Rs.12000, the capital is ______ a)Rs 25000 b)Rs 30000 c)Rs 35000 d)Rs 40000 e)Rs 45000
Ans. Let the total capital be X Money spend a s salary = 40/100 * X = 2X / 5 Money spend on purchasing commodities = 30/100 * X = 3X / 10 The remaining money is given as Rs 12000 so X - (2X/5 + 3X/10) = 12000 so X - (4X/10 + 3X/10) = 12000 so 3X/10 = 12000 X = 12000*10/3 = Rs. 40000
40. A sum lent at 8% per annum will yield as much simple interest in 3 years as Rs. 2500 lent at 4% per annum yields in 3 years. The sum is ______ a)1210 b)1750 c)2250 d)1250 e)2750
Ans. S.I = P x R x T /100 S.I => Simple interest P => Principal R => Rate of interest T => Time in years let the sum lent be P P x 8 x 3 / 100 = 2500 x 4 x 3 / 100 => P x 8 x 3 / 100 = 300 => P = 1250
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