What should come in place of the question mark in the following number series?
4, 2.5, 3.5, 6.75, 15.5, ?, 126.75
1
2.5
2
3.5
3
6.5
4
15.5
5
41.25
What should come in place of the question mark in the following number series?
4, 2.5, 3.5, 6.75, 15.5, ?, 126.75