Select the option that is related to the fifth number in the same way as the second number is related to the first number and the fourth number is related to the third number.

8 : 32 :: 12 : 72 :: 18 : ?

162

Pattern followed is :

( 1st term ÷ 2 ) × (1st term) = 2nd term

8 : 32

( 8 ÷ 2 ) × (8) = 32

12 : 72

( 12 ÷ 2 ) × (12) = 72

Similarly ,

18 : ?

( 18 ÷ 2 ) × (18) = 9 × 18 = 162

162 , is correct answer .