Question

Катер против течения реки за 5 часов проплыл 60 км пути. За какое время катер проплывет обратный путь, если скорость течения реки 4 км/час?

Answer 1

60 : 5 = 12км/ч - против течения
12 + 4 + 4 = 20км/ч - скорость по течению
60 : 20 = 3ч
Ответ: за 3 часа

Answer 2

Problem Analysis

To solve this problem, we can use the formula: time = distance / (speed of boat + speed of current)

Given: - Speed of boat (against the current) = 60 km in 5 hours - Speed of current = 4 km/h

Solution

Using the formula, we can calculate the speed of the boat against the current and then use it to find the time for the return journey.

1. Calculate the speed of the boat against the current: - Speed of boat against the current = (60 km / 5 hours) - 4 km/h.

2. Calculate the time for the return journey: - Time = 60 km / (speed of boat - speed of current).

Calculation

1. Calculate the speed of the boat against the current: - Speed of boat against the current = (60 km / 5 hours) - 4 km/h - Speed of boat against the current = (12 km/h) - 4 km/h - Speed of boat against the current = 8 km/h

2. Calculate the time for the return journey: - Time = 60 km / (speed of boat - speed of current) - Time = 60 km / (8 km/h) - Time = 7.5 hours

Answer

The boat will take 7.5 hours for the return journey.