Driving from Shanghai to Nanjing, we originally planned to arrive at 11:30 noon, but the speed increased by one-seventh after departure, and we arrived at 11 o'clock. Returning the next day, the same

Driving from Shanghai to Nanjing, we originally planned to arrive at 11:30 noon, but the speed increased by one-seventh after departure, and we arrived at 11 o'clock. Returning the next day, the same time

The distance between Shanghai and Nanjing is 288 kilometers.

1. When going

Planned speed: actual speed = 7:8, time ratio is 8:7, one minute difference (30 minutes), so the planned time is 8*30=240 points.

2. When returning

Planned speed: actual speed = 6:7, time ratio is 7:6, one minute difference (20 minutes), so the planned time is 7*20=140 points.

The difference of 240-140=100 points is the time to travel 120 kilometers, and the planned speed is 120/100=1.2 kilometers.

So, distance=1.2*240=288 kilometers.

Introduction

Proportions are divided into scale bars and ratios. An expression that expresses the equality of two ratios is called a proportion. To determine whether two ratios can form a ratio, you need to see whether their ratios are equal.

In a ratio, the product of two external terms is equal to the product of two internal terms. If you know any three terms in a ratio, you can find the other unknown term in the ratio. Finding the unknown terms in a ratio is called solving the ratio. The basic properties of proportion are used to solve proportions. Because the product of two external terms is equal to the product of two internal terms, we can multiply the two external terms and the internal terms by each other and then solve this equation.