python计算概率问题

这是个模拟购买彩票的题，有一组固定的中奖号码，然后每次会随机给出一组号码，来进行匹配，看是否中奖，这里我已经写好了。
我的问题是：如果我还想算出要买多少张彩票才能至少中3个白球，这该怎么写。求帮我解答一下

```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")

```

写个循环计数就行

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")
cnt=0
x=0
while cnt<3:
    mywhite = random.randint(1,69)
    if mywhite in white:
        cnt+=1
    x+=1
print('至少'+str(x)+'次')