What should come in place of the question mark '?' in the following number series?
2.5, 6.5, 15.5, 31.5, ?, 92.5
1
58.5
2
62.5
3
56.5
4
60.5
5
48.5
What should come in place of the question mark '?' in the following number series?
2.5, 6.5, 15.5, 31.5, ?, 92.5