Number System When (21)² is subtracted from the square of a number the answer obtained is 1584. What is the number ? 35 45 55 65 35 45 55 65 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 bag contains four red, six black and seven green balls. Three balls are drawn randomly. What is the probability that the balls drawn contain exactly two red balls ? 45/340 51/340 39/340 58/340 45/340 51/340 39/340 58/340 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Total balls = 4 + 6 + 7 = 17∴ n(S) = 17C1 = 680Two red balls can be selected from four red balls in 4C2 = 6 ways.and the third ball can be selected from the remaining 13 balls in 13C1 = 13 ways.∴ P (E) = 13x6/680 = 39/340
Number System The difference between a two-digit number and the number obtained by interchanging the two digits is 63. Which is the smaller of the two numbers? 29 70 92 Cannot be determined 29 70 92 Cannot be determined ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the ten's digit be x and units digit by y.Then,(10x + y) - (10y + x) = 639(x - y) = 63x - y = 7Thus, none of the numbers can be determined.
Number System 486+32×25—59=? 528 596 582 567 528 596 582 567 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP 528
Number System What is the sum of 1 + 2 + 3+ ... + 27 ? 396 378 382 343 396 378 382 343 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Sum = 27 x (27 + 1)/2= 27 x 28/2= 27 x 14= 378
Number System In how many different ways can the letters of word "COLLEGE" be arranged ? 1240 1280 1260 1300 1240 1280 1260 1300 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Number of ways = 7!/2!2! = 1260(∵ L and E come twice)
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