If the letters are arranged in reverse order, what is the 15th letter?

C. N

In the series A, B, C, D, E, F, G, H, I, J, how many letters are before 'F'?

B. 5

What is the missing number in the series: 2, 6, 12, 20, ?, 42

B. 32

Find the missing number in the series: 5, 11, 23, 47, ?, 191

C. 97

What number should replace the question mark in the series: 1, 4, 9, 16, ?, 36

B. 25