Every summer in Zhongguancun, there is always a big watermelon stall at the entrance of the 82nd floor. The stall owner is a man with a crooked neck, surnamed Wei. You don't have to knock when picking watermelons, you can listen with your ears. Because of this unique skill, it ranks among the eight strange vendors in Zhongguancun. Probably 1987 or 1988. Mathematicians Wang Yuan and his wife calculated the price while choosing.

Wei's crooked neck watermelon sells well, which will inevitably bring some trouble. Without weighing, it is divided into big melons and small melons, each with 3 pieces, and small melons 1 piece.

Seeing that the size difference between big melon and small melon is not very big, many people try their best to squeeze into small melon.

Mrs. Wang seems to be the same, but she heard Mr. Wang Yuan say, "Buy that big one."

"The big one is three times more expensive ..." Mrs. Wang hesitated.

"The big value is less than the low value," Mr. Wang said.

Mrs. Wang picked two big melons, paid for them, and seemed hesitant to see that everyone else was grabbing small melons.

Seeing her hesitation, Mr. Wang smiled and said, "What melon did you eat? Eat volume, not area. The radius of small melon is slightly weaker than that of big melon, but the volume is calculated in cubic. The small volume is less than 30% of the big one. Of course, you can make money by buying a big one. "

Mrs. Wang nodded and shook her head again. "Your calculation is wrong. Big watermelon is thick, small watermelon is thin. If you calculate the amount, I am afraid that you will still suffer from buying a big one. "

But seeing that Mr. Wang had answers, he nodded and said, "Hey, don't forget that the skin of that small watermelon is three melons, and the big watermelon is only 1. If you have more skin, you can calculate the surface area again. "

Madam Wang said, "I don't care about headaches." Two men went home with watermelons, leaving Wei with crooked hair.