The third grade car rental problem is really a headache! Summarized the problem-solving method for children to learn
There is one type of problem that is a headache in the three-year mathematics problem of primary school, that is, "renting a car". I don't know if parents have a headache when they are tutoring their children, or if they can't teach their children's troubles.
- Problem-solving confusion
It is easy for children to get confused when they encounter this kind of problem again. They don’t know how to write. They often finish writing the number of large cars, forget the number of small cars, or make a mess. Calculating the number of seats and rent is also full of errors.
The picture below is written by the child after repeated thinking. Basically, the problem is not big, but there are still mistakes. If you are careful, you may not find it.
Second, the idea of teaching materials
Generally, this kind of question is to find the most economical way to rent a car. The method of the teaching material is the table method. Start with a large car, start with 0 large cars, and see how many cars you need to sit down; then look at 1 large car and how many cars you need, until the number of cars is 0. By comparing several options, find the one with the least vacant seats and the least rent.
This car rental problem is an example problem in three mathematics books. There is no complete answer to the example problem, but only incomplete problem-solving ideas. This Beijing Normal University textbook is really flawed! No way, the child uses this teaching material, and can only teach the child little by little.
Starting from 0 carts, when the number of carts is 0, the number of small cars is 4, and the number of people can be 48, which meets the requirements of the number of people, and the rent is 480 yuan. This is plan 1. According to this line of thinking, there are a total of 4 options. After comparing option 3, the most economical option is to rent 2 large cars and 1 small car.
If we are 40 people, what is the cheapest way to rent a car? Those who are interested can count! See the picture at the end for the answer!
- Quick problem solving method
Because this kind of problem uses a large car as much as possible, and the rest of the people use a small car, the plan with the least empty seats and the least rent is the best plan.
In fact, it is mainly solved by division. Divide the total number of people 48 by the maximum number of 18 people in each large car, which is equal to 12 people in 2 large cars, and then divide 12 people by the number of 12 people in each small car, which is equal to 1 small car. So renting 2 large cars and 1 small car is the most economical.
Cart: 48÷18=2 (vehicles)...12 (persons)
Car: 12÷12=1 (car)
A: It is the most economical to rent 2 large cars and 1 small car.
Can you do question 3 on the picture? I provide a list format method here, please answer the formula method in the comment area!