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

C. 97

A, B, C, D, and E are five students with the following grades: A is better than B but worse than C. D is better than E but worse than A. Who has the highest grade?

C. C

In a race, the following conditions apply: Runner A finished before Runner B but after Runner C. Runner D finished after Runner A but before Runner E. Who finished last?

D. E

Among six friends: P, Q, R, S, T, and U, the following conditions are given: P is older than Q but younger than R. S is older than T but younger than U. Who is the youngest?

B. Q

Complete the series: 10, 20, 40, 80, ?, 320.

A. 160