There are 5 consecutive numbers starting with 1, so the numbers are
1,2,3,4,5 in the exact same order.
Suppose we use binary search to search for '1'.
then there will be three comparisons to find the number 1.
- First we will check the middle element i.e, 3
- Then we will check the left sub-array's middle element i.e, 2
- And we continue in this manner till we find 1
So we will need 3 comparisons to find 1.
Likewise we will need,
2 comparisons to find 2,
1 comparison to find 3,
2 comparisons to find 4,
3 comparisons to find 5.
Hence totally we need $3+2+1+2+3 = 11$ comparisons.
The Average no. of Comparisons will be $11/5 = 2.2$
So the answer is $2.2$