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 ? 91/190 92/190 89/190 90/190 91/190 92/190 89/190 90/190 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 (3² x 4² x 5) ÷ 36 = (?)² - 80 16 12 14 10 16 12 14 10 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP (?)² = 3² x 4² x 5/36 + 80= 20 + 80 = 100∴ ? = √100 = 10
Number System (√6 + 1)² = ? + 2√6 8 5 6 7 8 5 6 7 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP ? = (√6 + 1)² - 2√6= (√6)² + 2 x √6 + 1 + 1² - 2√6= 6 + 2√6 + 1 - 2√6 = 6 + 1 = 7
Number System √(17)² + (17)² + (5)² - 2 = ? 16 19 18 17 16 19 18 17 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP ? = √49 + 289 + 25 - 2 = √361 = 19
Number System If the sum of five consecutive even numbers A, B, C, D and E is 130, what is the product of A and E ? 660 720 840 780 660 720 840 780 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the consecutive even numbers be A = 2x, B = 2x + 2, C = 2x + 4, D = 2x + 6 and E = 2x + 8= A + B + C + D + E = 130= 10x + 20 = 130∴ x = 130 - 20/10 = 11Therefore, product of A and E= 22 x 30 = 660
EXAMIANS