What is the time complexity of searching for an element

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

15 : 5 :: 26 : (?)

Select the missing number from the given responses.

Find the missing number.

What will come in the place of question mark?

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

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

3.5 , ?,  8.3, 10.7, 13.1 , 15.5

F : 216 : : I : ?

Find the missing letter.