Question

In the following questions the following rules have been applied to the same set of numbers In every question find out which of the rules viz (1), (2), (3), (4) and (5) have been applied
Rules:
(1) Subtract thrice the number from its cube
(2) Multiply the number by 7 and subtract 3 from the result
(3) Add the number to its square
(4) Divide the number by 2 and add the square of the quotient to the number
(5) Multiply the number by 5 and add 5 to the result
20, 42, 72, 110

• A. Rule (1)
• B. Rule (2)
• C. Rule (3)
• D. Rule (4)

Answer 1

Answer: (C)

Rule (3)

Let us first located the numbers on which the questions are based Consider the rule number five It is clear that in this case the number must be a multiple of 5 So in Q 13 all numbers are multiple of 5 Let 'x' be a number so that according to rule (5) we have

5x + 5 = 25 or 35 or 45 or 55 so that x is 4 or 6 or 8 or 10 Thus the four numbers on which the question are based are 4, 6, 8, 10

Using rule no (1) on these numbers we have $4^3-3\times 4;6^3-3\times 6;8^3-3\times 8;{10}^3-3\times 10or52$ 198, 488, 970 which is question 12

Using rule no (2) we have 7 x 4 - 3; 7 x 6 - 3; 7 x 8 - 3; 7 x 10 - 3 or 25, 39, 53, 67 which is question 15

Using rule no (3) We have $4+4^2;6+6^2;8+8^2;10+{10}^2$ or 20, 42, 72, 110 which is question 11

Using rule no (4) we have $4+{\left(\frac{4}{2}\right)}^2:6+{\left(\frac{6}{2}\right)}^2:8+{\left(\frac{8}{2}\right)}^2:10+{\left(\frac{10}{2}\right)}^2$ or 8, 15, 24, 35 which is question 14

Using rule no (5) we have question 13 Hence from questions 11 to 15 the rules applied are (3); (1); (5); (4); (2)