Dongdong and his parents go to the barber shop for a haircut. The three of them can only send hair one by one, mom ZACC 30 minutes, dad ZACC (haircut) 15 minutes, and Winter ZACC 10 minutes. Then the question comes, how should we arrange their zdacc (haircut) order to minimize the total waiting time of three people?

Answer: No matter what their order is, the total waiting time of three people is the same, *** 1 10 minute.

For example: (1) In the order of "Dong Dong-Dad-Mom", Dad waited 10 minute, Mom waited 15 minute, Dad waited 15 minute, and Mom waited 15 minute. So they add up to10+(10+15)+(15+30)+30 =110 minutes.

(2) Dad-Mom-Dongdong, push by yourself, which is also 1 10 minutes.

So this topic is an idiot question, which is meaningless!

Perhaps the real original problem is that you don't need to wait one by one, depending on how many minutes it takes, please ask the math teacher to continue mink.