Question

Катер, плывущий по течению реки, за 7 часов проплыл 157,5 км Какой путь проплывёт катер против течения реки за 3,2 часа, ес- ли скорость течения реки 3,5 км/час?

Answer 1

Ответ:

49,6км

Пошаговое объяснение:

1) 157,5:7=22,5(км/ч)- скорость катера по течению.

2) 22,5-3,5=19(км/ч)- собственная скорость катера.

3) 3,2*19=60,8(км)- просто проплывёт катер.

4) 3,2*3,5=11,2(км)- против течения.

5) 60,8-11,2=49,6(км)- проплывёт катер за 3,2 часа против течения реки.

Ответ:49,6км

Answer 2

Problem Analysis

We are given that a boat traveled 157.5 km downstream in 7 hours. We need to find out how far the boat will travel upstream in 3.2 hours, given that the river's current is flowing at a speed of 3.5 km/h.

Downstream Speed Calculation

To solve this problem, we need to understand the concept of relative speed. When the boat is traveling downstream, its speed is the sum of its own speed and the speed of the river's current. Let's denote the boat's speed as b km/h and the speed of the river's current as c km/h.

Therefore, the boat's downstream speed is (b + c) km/h.

Downstream Distance Calculation

We are given that the boat traveled 157.5 km downstream in 7 hours. We can use the formula distance = speed × time to calculate the downstream speed.

Therefore, the downstream distance is (b + c) × 7 km.

Upstream Speed Calculation

When the boat is traveling upstream, its speed is the difference between its own speed and the speed of the river's current. Therefore, the boat's upstream speed is (b - c) km/h.

Upstream Distance Calculation

We need to find out how far the boat will travel upstream in 3.2 hours. We can use the formula distance = speed × time to calculate the upstream distance.

Therefore, the upstream distance is (b - c) × 3.2 km.

Solving the Problem

To solve the problem, we need to find the value of b (the boat's speed) using the given information.

We know that the downstream distance is 157.5 km and the downstream time is 7 hours. Therefore, we can set up the equation:

(b + 3.5) × 7 = 157.5

Simplifying the equation, we have:

7b + 24.5 = 157.5

Solving for b, we get:

7b = 133

b = 19

Now that we have the value of b, we can calculate the upstream distance using the formula:

(19 - 3.5) × 3.2

Simplifying the equation, we have:

15.5 × 3.2 = 49.6

Therefore, the boat will travel 49.6 km upstream in 3.2 hours.

Answer

The boat will travel 49.6 km upstream in 3.2 hours, given that the river's current is flowing at a speed of 3.5 km/h.

Source:

- 'Untitled' - snippet: ```... , ... 3 ). 2) x = 2k. 22* 2 =15, (2* ) (2* + )...```