python 习题4

 2.

list = [68, 75, 32, 99, 78, 45, 88, 72, 83, 78]
a = b = c = d = 0

for i in list:
    if i in range(90, 100):
        a += 1
    elif i in range(80, 89):
        b += 1
    elif i in range(60, 79):
        c += 1
    else:
        d += 1

print("等级为优的人数为：", a, "n等级为良的人数为：", b, "n等级为中的人数为：", c, "n等级为差的人数为：", d)

4.

student = {
    "a": 50, "g": 45,
    "b": 45, "j": 45,
    "q": 45, "n": 45,
    "w": 45, "l": 45,
    "e": 45, "m": 45,
}


def X(a):
    sum = 0
    for i in a.values():
        sum += i
    return sum / len(a)


print("学生姓名和成绩如下：")
print(student)
print("总人数为", len(student), "平均分为", X(student))