Problem on Number

1.If one-third of one-fourth of a number is 10, then three-tenth of that number is: A)34 B)42 C)36 D)32 Answer : Option C Explanation: Let the number be x. Then, 1/3 of 1/4 of x = 10 => x = 12 x 10 = 120. So, required number =((3/10) x 120)= 36. 2.The sum of the digits of a two-digit number is 11 and the difference between the digits is 3. What is the two-digit number? A)47 B)83 C)74 D)can not be determined Answer : Option D Explanation: Let the ten's digit be x and unit's digit be y. Then, x + y = 11 and x - y = 3 or y - x = 3. Solving x + y = 11 and x - y = 3, we get: x = 7, y = 4. Solving x + y = 11 and y - x = 3, we get: x = 4, y = 7. So, the number is either 74 or 47. Hence, the number cannot be determined. 4. find a positive number which when increased by 15 is equal to 50 times the reciprocal of the number. A)6 B)7 C)5 D)4 Answer : Option C Explanation: Let the number be x. Then, x + 15 = 50/x x2 + 15x - 50 = 0 (x + 10)(x - 5) = 0 x = 5. 5. A number exceeds by 15 from its 3/6 part. Then the number is? A)26 B)35 C)45 D)25 Answer : Option D Explanation: x – 3/6 x = 15 x = 25 3.A number consists of two digits. If the digits interchange places and the new number is added to the original number, then the resulting number will be divisible by: A)8 B)9 C)10 D)12 Answer : Option D Explanation: Let the ten's digit be x and unit's digit be y. Then, number = 11x + y. Number obtained by interchanging the digits = 11y + x. (11x + y) + (11y + x) = 12(x + y), which is divisible by 12.

« 1 2 »