A student was asked to divide a number by 6 and add 12 to the quotient. He, however first added 12 to the number and then divided it by 6, getting 112 as the answer. The correct answer should have been
Answer: A Let the number be x, then operations undertook by the student = (x+12)/6 =112 => x = 660. Correct answer = 660/6 + 12 = 122.
Q. No. 2:
If Dennis is 1/3 rd the age of his father Keith now, and was 1/4 th the age of his father 5 year ago, then how old will his father Keith be 5 year from now?
Answer: D Let the present age of Dennis and his father be x and y respectively. Then, x = y/3...............(i) and (x-5) = (y-5)/4......(ii) On solving both equation we get y= 45 year. Hence, required age = (y+5) = 50 year
Q. No. 3:
Two spinning machines A and B can together produce 3,00,000 m of cloth in 10 hour, if machine B alone can produce the same amount of cloth in 15 hour, then how much cloth can machine A produce alone in 10 hour?
Answer: B Machines A and B together will produce 30,000 m of cloth in 1 hour. Machine B alone can produce 20,000 m cloth in 1 hour. Therefore, Machine A can produce 10,000 m cloth in 1 hour. So, in 10 hour Machine A can produce 1,00,000 m of cloth.
Q. No. 4:
The ages of the two persons differ by 20 years. If 5 year ago, the older one be 5 times as old as the younger one, then their present ages, in year are
Answer: C 1 candle is made from 9 stubs Therefore, 116 candles will be made from 1044 stubs From 116 candles, 12 candles can be made with 8 stubs left. Now total stubs left = (12+8) = 20 out of which two candles can be made with two stubs left. Thus, Maximum number of candles that can be made = (116+12+2) = 130.
Q. No. 6:
A, B and C are three typists, who working simultaneously can type 216 pages in four hours. In one hour, C can type as many pages more than B as B can type more than A. During a period of five hours, C can type as many pages as A can during seven hours.How many pages does each of them type per hour respectively?
Answer: D Let A's typing in 7 hour be x pages. Then his 1 hour typing = x/7 pages. C's typing in 5 hour = x pages Then his typing in 1 hour = x/5 pages. B's typing in 1 hour = (x/5 + x/7)/2 = 6x/35 4(18x/35) = 216 => x= 105. Required ratio = 105/7 : 105/5 : 105* 6/35 => 15:18:21