Q: If a2 = 12, then a4 =?
Solution: Given a x a = 12 asked to find a x a x a x a = (a x a) x (a x a) a4 = a2 x a2 = 12 x 12 = 144. More :: Mathematical operations questions and answers. The correct answer is: A) 144
Q: A tap can fill a tank in 6 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely?
Solution: Time taken by one tap to fill half of the tank = 3 hrs. Part filled by the four taps in 1 hour =4*1/6 =2/3 Remaining part =1-12=12 23:12::1:x => x = 12*1*32=34 So, total time taken = 3 hrs. 45 mins. The correct answer is: B) 3 hrs 45 min
Q: A student was asked to find the arithmetic mean of the numbers 3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and x. He found the mean to be 12. What should be the number in place of x ?
Solution: Clearly, we have (3 + 11 + 7 + 9 + 15 + 13 + 8 + 19 + 17 + 21 + 14 + x) / 12 = 12. or 137 + x = 144 or x = 144 - 137 = 7. The correct answer is: B) 7
Q: If each edge of a cube is increased by 50%, find the percentage increase in Its surface area
Solution: Let the edge = a cm So increase by 50 % = a + a/2 = 3a/2 Total surface Area of original cube = 6a2 TSA of new cube = 63a22 =69a24= 13.5a2 Increase in area = 13.5a2-6a2 =7.5a2 7.5a2 Increase % =7.5a26a2×100 = 125% The correct answer is: A) 125%
Q: What annual payment will discharge a debt of Rs.7620 due in 3years at1623 % per annum interest?
Solution: Let each installment be Rs.x. Then, (P.W. of Rs.x due 1 year hence) + (P.W of Rs.x due 2 years hence) + (P.W of Rs. X due 3 years hence) = 7620. x1+503x100+x1 +503x1002+x1 +503x1003 = 7620 6x7+36x49+216x343=7620 294x + 252x + 216x = 7620 x 343 => x = 3430 Amount of each installment = Rs.3430 The correct answer is: C) 3430
Q: Find the odd number in the following number series? 24, 4, 13, 41, 151, 640
Solution: The given number series follows the pattern that, 24×0 + 4 = 4 4×1 + 9 = 13 13×2 + 16 = 42 42×3 + 25 = 151 151×4 + 36 = 640 Therefore, the odd number in the given series is 41 The correct answer is: C) 41
Q: The sale price of an article including the sales tax is Rs. 616. The rate of sales tax is 10%. If the shopkeeper has made a profit of 12%, then the cost price of the article is :
Solution: 110% of S.P. = Rs. 616 S.P. = (616 x 100)/110 = Rs. 560 C.P = (110 x 560)/112 = Rs. 500 The correct answer is: C) Rs. 500
Q: The cost price of a Rs.100 stock at 4 discount, when brokerage is 14% is
Solution: CP. =Rs.100-4+14 = Rs.96.25 The correct answer is: C) Rs.96.25
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