T = int(input())
for i in range(T):
    n = int(input())
    a=list(map(int,input().split()))
    avg = sum(a)/len(a)
    c = max(a)-min(a)
    b=0
    for j in a:
        b  += (j-avg)**2
    print(f'{c} {b/len(a):.3f}')

理解循环的包含关系