题解 | 牛牛的数学作业

T=int(input().strip())
for i in range(T):
    n=int(input().strip())
    a=list(map(int,input().split()))
    range_a=max(a)-min(a)
    avg_a=sum(a)/len(a)
    sum_a=0
    for i in range(len(a)):
       square_a=pow((a[i]-avg_a),2)
       sum_a=sum_a+square_a
    variance_a=sum_a/len(a)
    #print("{} {:.3f}".format(range_a,variance_a))
    print(f"{range_a} {variance_a:.3f}")