Mathematical model paper 1

Today is another sunny day. I was wandering in the street when I suddenly saw a lot of people gathered not far away. I ran for a year, and the result was a prize-winning game. "Hum, what's fun about winning the prize?" I was bored when the person next to me quickly said, "It's not fun to grab the prize, but there is a big prize that can attract people."

I asked eagerly, "What is it!" "50 yuan money." The man with big eyes said. I'm very excited to hear that. "I have to try anything for such an attractive prize." Then I asked the shopkeeper how to grasp the rules. The shopkeeper said, "This is 24 Mahjong, and it says 12 5, 12 10. You can only catch 12 mahjong at a time. If the total number of 12 mahjong targets is 60, then you can win the 50 yuan Prize. " Without rolling up my sleeves, I took out 5 yuan money from my pocket and gave it to the shopkeeper.

Mathematical model ii

Today, my mother and I went to the bookstore to buy books. I found a puzzle in a book called Interesting Mathematics. The problem is this: Bill spent 10 yuan bought a dog, sold it 15 yuan, then spent 20 yuan to buy it, and finally spent 25 yuan to sell it. Did Bill finally make money or lose money? I think buying and selling, selling and buying, over and over again, thinking has been doing.

We need to find out.

I went to ask my mother, and she said, "If you can classify according to the number of' buying' and' selling', you will be suddenly enlightened. I think: the money used for "buying" is 10+20=30 (yuan). Money earned by "selling": 15+25=40 (yuan). Obviously, Bill made money, earning 40-30= 10 yuan! What a rich knowledge of mathematics!