Number System When (21)² is subtracted from the square of a number the answer obtained is 1584. What is the number ? 65 35 55 45 65 35 55 45 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the number be x.According to the question,x² - (21)² = 1584= x² - 441 = 1584 = x² = 1584 + 441 = 2025∴ x = √2025 = 45
Number System A two-digit number is such that the product of the digits is 8. When 18 is added to the number, then the digits are reversed. The number is: 24 42 18 81 24 42 18 81 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the ten's and unit's digit be x and 8/x respectively. Then, (10x + 8/x) + 18 = 10 * 8/x + x 9x2 + 18x - 72 = 0 x2 + 2x - 8 = 0 (x + 4)(x - 2) = 0 x = 2 So, ten's digit = 2 and unit's digit = 4. Hence, required number = 24.
Number System If one-third of one fourth of a number is 15, then three-tenth of that number is: 25 54 45 35 25 54 45 35 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the number be x. Then,1/3 of 1/4 of x = 15x = 15 * 12 = 180So, required number = (3/10 * 180) = 54.
Number System Which one of the following numbers is exactly divisible by 11? 415624 315624 235641 245642 415624 315624 235641 245642 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP (4 + 5 + 2) - (1 + 6 + 3) = 1, not divisible by 11.(2 + 6 + 4) - (4 + 5 + 2) = 1, not divisible by 11.(4 + 6 + 1) - (2 + 5 + 3) = 1, not divisible by 11.(4 + 6 + 1) - (2 + 5 + 4) = 0. So, 415624 is divisible by 11.
Number System The average of five consecutive even numbers A, B, C, D and E is 42. What is the product of B and D ? 2476 3289 1760 4589 2476 3289 1760 4589 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP A + B + C + D + E/5 = 42∴ C = 42, ∴ B = 40, ∴ D = 44∴ B x D = 40 x 44 = 1760
Number System The product of two natural numbers is 17. Then, the sum of the reciprocals of their squares is: 290/289 289 1/289 289/290 290/289 289 1/289 289/290 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the numbers be a and b. Then,ab = 17, a = 1 and b = 17So, 1/a2 + 1/b2 = (a2 + b2)/a2 b2 = (12 + 172)/(1 * 17)2 = 290/289
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