Find the missing number.

15 Select the number from among the given options that can replace the question mark (?) in the following series.

24, 48, 51, 204, 209, ?

Select the number from among the given option that can replace the question mark (?) in the following series.

6, 31, 126, 381, 766, ?

Select the number from among the given options that can replace the question mark (?) in the following table.

F : 216 : : I : ?

Choose the correct alternative from the given ones that will complete the series.

3.5 , ?,  8.3, 10.7, 13.1 , 15.5

Select the number from the given option that can replace the question mark (?) in the following series:

32, 16, 24, 60, ?, 945

19 : 109 ∷ 21 : ?

Study the given pattern carefully and select the number that can replace the question mark (?) in it.