The first volume of the first day of junior high school 100 mathematical application problems are simple rational numbers.

1. There is a wire. For the first time, less than half of it was used 1 m, and for the second time, half of it was used, and the remaining thread exceeded 1 m. As a result, there are still 2.5 meters left in the wire. How long is this wire?

2. Pour a bucket full of water in a cylindrical bucket with an internal diameter of 200mm into rectangular iron boxes with internal length \ width \ height of 300mm.300mm.80mm respectively, and fill them up. How high is the water in the cylindrical barrel?

The train was blocked halfway, delayed for 6 minutes, and then the speed was increased from 40 kilometers to 50 kilometers per hour. How many kilometers can I make up for the delay?

4. A seventh-grade (1) class of a school organizes extracurricular activities, prepares to hold a badminton competition, and goes to the store to buy badminton rackets and shuttlecocks. 25 yuan for each racket, 2 yuan for each ball. Store A said "Badminton and racket are 10% off", while Store B said "Buy one racket and get two shuttlecocks. (1) The school is going to spend all the money from 90 yuan to buy two shuttlecocks. (2) If you have to buy two pairs of badminton rackets, how many pairs should you buy in two stores?

Three students, A, B and C, donated books to children in poor areas. It is understood that the proportion of books donated by these three students is 5:6:9.

If the sum of the books donated by two students, A and C, is twice that donated by B, that is, 12, then how many books did they each donate?

Reference answer:

1. Solution: This line was originally x meters long.

x-[ 1/2( 1/2X- 1)+ 1]= 2.5

X=4

2. solution: the height is Xmm

100 100лX = 300 300 80

X = 720Л

3. Solution: Walk X kilometers.

X/50=[X-(40 6/60)]/40

X=4

4.a: After 10% discount, the racket is 22.5 yuan/piece.