In the series 1, 3, 6, 10, what is the next number?

A. 15

What is the next term in the series: 5, 10, 20, 40?

C. 80

Which of the following groups of letters follows the same pattern as the group: A, D, G, J?

A. B, E, H, K

What is the next letter in the series: X, W, V, U, T?

A. S

Identify the next letter in the series: Z, Y, X, W, ?

A. V