Question

Пароход проплыл по течению реки 180 км за 9 ч.За какое время он пройдет обратный путь;если его скорость уменьшится на 3 км\ч?Написать краткую запись таблицей

Answer 1

180:9=20 км/ч 20-3=17 180:17

Answer 2

Problem Analysis

We are given that a steamboat traveled 180 km downstream in 9 hours. We need to find out how long it will take for the steamboat to travel the same distance upstream if its speed decreases by 3 km/h.

Solution

Let's analyze the problem step by step:

1. Downstream Speed: We are given that the steamboat traveled 180 km downstream in 9 hours. To find the downstream speed, we can divide the distance traveled by the time taken: Downstream Speed = Distance / Time. Substituting the given values, we get Downstream Speed = 180 km / 9 hours = 20 km/h.

2. Upstream Speed: We are told that the steamboat's speed decreases by 3 km/h. Therefore, the upstream speed will be 3 km/h less than the downstream speed. Substituting the values, we get Upstream Speed = Downstream Speed - 3 km/h = 20 km/h - 3 km/h = 17 km/h.

3. Upstream Time: To find the time taken to travel the same distance upstream, we can divide the distance by the upstream speed: Upstream Time = Distance / Upstream Speed. Substituting the given values, we get Upstream Time = 180 km / 17 km/h.

Let's summarize the solution in a table:

| | Distance (km) | Speed (km/h) | Time (hours) | |---|---------------|--------------|--------------| | Downstream | 180 | 20 | 9 | | Upstream | 180 | 17 | ? |

From the table, we can see that the time taken to travel the same distance upstream is 180 km / 17 km/h.

Answer

The steamboat will take approximately 10.59 hours to travel the same distance upstream if its speed decreases by 3 km/h.

Calculation

To calculate the exact time, we can divide the distance by the speed using the formula Time = Distance / Speed:

Upstream Time = 180 km / 17 km/h = 10.5882 hours (rounded to two decimal places).

Therefore, the steamboat will take approximately 10.59 hours to travel the same distance upstream if its speed decreases by 3 km/h.

Please let me know if I can help you with anything else.