python算概率问题

买彩票,然后要算出至少买多少张彩票才能中三个白球。
以下是我的代码:


```python
import random

print("Buy a ticket with 5 white balls [not identical, between 1-69] and 1 red ball [between 1-26]")
mywhite = random.sample(range(1, 69), 5)
myred = random.randint(1, 26)

white = [32, 35, 40, 52, 54]
red = 1
print("Your selection for white balls are: ", *mywhite )
print("Your selection for red balls is: ", myred )
print("Winning numbers for white balls:", *white)
print("Winning number for red ball:", red)
matchwhite = 0
for i, j in zip(mywhite, white):
    if i == j:
        matchwhite += 1
matchred = 1 if myred == red else 0
if matchwhite == 0 and matchred ==0:
    print ("No matching. Thanks for your contribution!")
elif matchred:
    if matchwhite == 0:
        print ("Matching only the red ball: $4")
    elif matchwhite == 1:
        print ("Matching the red ball and one white ball: $4")
    elif matchwhite == 2:
        print ("Matching the red ball and two white balls: $7")
    elif matchwhite == 3:
        print ("Matching the red ball and three white balls: $100")
    elif matchwhite == 4:
        print ("Matching the red ball and four white balls: $10,000")
    else:
        print ("Matching five white balls and the red ball: Jackpot")
else:
    if matchwhite == 3:
        print ("Matching three white balls: $7")
    elif matchwhite == 4:
        print ("Matching four white balls: $100")
    else:
        print ("Matching five white balls: $1,000,000")

求大神能帮我解答一下,感激不尽!!

```

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