好像还是关于概率的，请指教大侠们！！

Michelle_winnerUID: 2719084

Given that a vending machine dispense gumballs in a regularly repeating cycle of ten different colors, if a quarter buy 3 gumballs, what is the minimum amount of money that must be spent before 3 gumballs of the same color are dispensed?

scott_umacUID: 2414907

I think this is not a problem on Probability. Vending machine dispense gumballs in a regularly repeating cycle,  not randomly。
You have to buy at least 21 gumballs before 3 gumballs of the same color are dispensed。
*#########*#########*
* stands for the color, # stands for other colors.
Which is 21/3= 7 quarters
If I am wrong, please correct me.

tianrunheUID: 2474327

0.25 / 3 * 21 = $1.75

Michelle_winnerUID: 2719084

首先谢过
我也这么想的，但不知道为什么印度网上的结果是5dollars and 1 quarter.

is there anyone can show us why?

thanks.

scott_umacUID: 2414907

他们的答案经常有错误的 呵