题解 | 牛牛的数学作业

T = int(input())
for i in range(T):
    n = int(input())
    a = list(map(int,input().split())) # 接收输入
    mean = sum(a) / len(a)
    variance_value = sum((x - mean) ** 2 for x in a) / len(a) # 计算方差
    print(f'{max(a)-min(a)} {variance_value:.3f}')