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Q: Select the number from among the options given that is related to the fifth number in the same way as the second and fourth numbers are related to the first and third numbers respectively 11 : 143 :: 13 : 221 :: 7 : ?
  • A. 35
  • B. 56
  • C. 57
  • D. 77
Correct Answer: Option D - On multiplying into 11 to its next prime number – 11×13 = 143 Similarly, on multiplying into 13 to its next prime number = 13×17 = 221 Same as, on multiplying into 7 to its next prime number = 7×11 = 77 11 : 143 :: 13 : 221 :: 7 : 77 Hence, ? = 77
D. On multiplying into 11 to its next prime number – 11×13 = 143 Similarly, on multiplying into 13 to its next prime number = 13×17 = 221 Same as, on multiplying into 7 to its next prime number = 7×11 = 77 11 : 143 :: 13 : 221 :: 7 : 77 Hence, ? = 77

Explanations:

On multiplying into 11 to its next prime number – 11×13 = 143 Similarly, on multiplying into 13 to its next prime number = 13×17 = 221 Same as, on multiplying into 7 to its next prime number = 7×11 = 77 11 : 143 :: 13 : 221 :: 7 : 77 Hence, ? = 77