4、输出一个3×5矩阵每行的平均值（元素为1~100的随机整数）。

好的，这是一个简单的 Python 代码实现：

import random

# 生成3x5的矩阵，元素为1~100的随机整数
matrix = [[random.randint(1, 100) for j in range(5)] for i in range(3)]

# 输出矩阵
for i in range(3):
    for j in range(5):
        print(matrix[i][j], end=' ')
    print()

# 计算每行的平均值并输出
for i in range(3):
    row_avg = sum(matrix[i]) / 5
    print(f"The average of row {i+1} is {row_avg}")

输出结果类似于：

99 12 84 62 52 
76 26 15 23 35 
64 81 27 90 98 
The average of row 1 is 61.8
The average of row 2 is 35.0
The average of row 3 is 72.0

希望能够帮到你！