Number System An urn contains 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white ? 89/190 91/190 90/190 92/190 89/190 91/190 90/190 92/190 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Total possible outcomes = 20C2 = 20 x 19/1 x 2 = 190Total favourable outcomes = 7C1 x 13C1 = 7 x 13 = 91∴ Required probability = 91/190
Number System In a two-digit number, if it is known that its unit's digit exceeds its ten's digit by 2 and that the product of the given number and the sum of its digits is equal to 144, then the number is: 46 24 26 42 46 24 26 42 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the ten's digit be x. Then, unit's digit = x + 2. Number = 10x + (x + 2) = 11x + 2 Sum of digits = x + (x + 2) = 2x + 2 (11x + 2)(2x + 2) = 144 2x2 + 26x - 140 = 0 (x - 2)(11x + 35) = 0 x = 2Hence, required number = 11x + 2 = 24.
Number System Find the least number with which 16200 should be multiplied, to make it a perfect cube. 36 360 45 48 36 360 45 48 ANSWER DOWNLOAD EXAMIANS APP
Number System Two numbers have a H.C.F of 16 and a product of two numbers is 2560. Find the L.C.M of the two numbers? 170 150 160 140 170 150 160 140 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP L.C.M of two numbers is given by(Product of the two numbers) / (H.C.F of the two numbers) = 2560/16 = 160.
Number System In how many ways can 5 boys be chosen from 6 boys and 4 girls so as to include exactly one girl ? 56 54 60 58 56 54 60 58 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP One girl can be chosen in 4C1 = 4 ways and 4 boys can be chosen in 6C4 = 15 ways ∴ Total number of ways = 4 x 15 = 60 ways.
Number System {(742)² ÷ 36} ÷ 2 = ? 420.5 422.5 423.5 421.5 420.5 422.5 423.5 421.5 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP ? = (174 x 174/36) ÷ 2 = 841/2 = 420.5
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