What letters will fill the blank?

Z, X, V, T, R, __,__

In the following question, select the missing number from the given series.

9, 10, 13, 22, 49, ?

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

100, -20, 4, ? , 0.16, -0.032

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

3, 5/3, 1/3, ? , -7/3, -11/3

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

1, 0.125, 1/27, 1/64, ? , 1/216

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

6, 18, 54, ? , 486, 1458

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

111, 107.5, 104, ? , 97, 93.5

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

-0.5, -0.35, -0.2, -0.05, ? , 0.25

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

4, 5.2, 6.4, ?, 8.8