Select the option that is related to the sixth number in the same way as the first number is related to the second number and the third number is related to the fourth number.
124 : 4 :: 217 : 7 :: ? : 9

Correct option is B

Given: 124 : 4 :: 217 : 7 :: ? : 9
Logic: 2nd number 31 = 1st number
124 : 4 → 4 31 = 124
and
217 : 7 → 7 31 = 217
Similarly,
? : 9 → 9 31 = 279
Correct answer is (b) 279.