Identify the missing number in the series: 12, 24, 36, ?, 60

B. 48

Identify the missing number in the series: 1, 4, 9, 16, ?, 36.

B. 25

Book : Author :: Painting : ?

A. ARTIST

Identify the missing number in the series: 5, 10, 20, 40, ?, 160.

A. 80

If the letter 'X' is the 24th letter of the alphabet, what is the 24th letter before 'X'?

A. T