Question

What is the missing number in sequence 3 5 9 blank 15?

Answer 1

The missing number is 11.

Explanation:

3+2=5; 5+4=9; The pattern is +2, +4.

3 + 2 = 5 ⇒ 5 + 4 = 9 ⇒ 9 + 2 = 11 ⇒ 11 + 4 = 15