Number System Which one of the following is the sum of the numbers 1, 3, 5, 7, 9…. up to nth number? N2 + 1 N(N + 1) N(N + 1)/2 N2 N2 + 1 N(N + 1) N(N + 1)/2 N2 ANSWER DOWNLOAD EXAMIANS APP
Number System The peresent age of the father and the son are in the ratio of 8:3. After 12 years the ratio of their ages will be 2:1. What is the sum of the present age of the father and the son ? 69 years 66 years 67 years 68 years 69 years 66 years 67 years 68 years ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the present age of the father be 'x' and that of the son be 'y'. Then x/y = 8/3∴ 3x = 8y Further, x + 12/y + 12 = 2/1 ∴ x + 12 = 2y + 24 ∴ x - 2y = 12 ......(ii)From eqn (i) and (ii), x = 48, y = 18 ∴ sum = 66 yrs.
Number System The sum of the numbers is 264. If the first number be twice the second and third number be one-third of the first, then the second number is: 54 72 48 84 54 72 48 84 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the second number be x. Then, first number = 2x and third number = 2x/3.2x + x + 2x/3 = 26411x/3 = 264x = 72
Number System I. 3x2-14x + 8 = 0 II. 2y2 - 1 7 y + 36 = 0 if x <= y if x > y if x < y if x >= y if x <= y if x > y if x < y if x >= y ANSWER EXPLANATION DOWNLOAD EXAMIANS APP l. 3x2 - 12x - 2x + 8 = 0or 3x(x - 4) -2 (x -4) = 0∴ x = 4, 2/3ll. 2y2 - 8y - 9y + 36 = 0or 2y (y - 4) -9 (y - 4) = 0or (2y - 9) (y - 4) = 0∴ y = 4, 9/2
Number System A basket contains 5 blue, 4 green and 3 red ball. If three balls are picked at random, what is the probability that at least one is red ? 37/52 31/58 32/51 34/55 37/52 31/58 32/51 34/55 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Probability of having no red ball is9C3 / 12C3 = 21/55Probability of having at least one red ball is 1 - 21/55 = 34/55
Number System The difference between 78% of a number and 59% of the same number is 323. What is 62% of that number ? Rs. 986 Rs. 926 Rs. 945 Rs. 1054 Rs. 986 Rs. 926 Rs. 945 Rs. 1054 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Let the number be x.78% of x - 59% of x = 323= 78x - 59x/100 = 323= 19x/100 = 323∴ x = 323 x 100/19 = 1700= 62% of 1700 = 1700 x 62/100 = 1054
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