Given an array arr of N integer elements, the task is to find sum of average of all subsets of this array.
The first line of input contains an integer T denoting the number of test cases. Then T test cases follow. The first line of each test case contains an integer N denoting the size of array A.
The second line of each test case contains N space separated integers denoting elements of the array A[ ].
Print the average of all the subsets of array A exactly upto 6 decimal places. Print the answer for each testcase in a new line.
1<= T <=100
1<= N <=20
1<= A[ ] <=100
2 3 5 7