Question

8). Скорость парома 9 км/ч, скорость течения реки 1 км/ч.За какое время паром проплывет 90 км по течению реки? а). 9 ч; б). 3 ч; в). 10 ч; г). 11 ч.

Answer 1

90/(9+1)=10 часов
Ответ: 10 часов

Answer 2

Problem Analysis

We are given the speed of a ferry and the speed of the river current. We need to determine how long it will take for the ferry to travel a distance of 90 km downstream.

Solution

To solve this problem, we can use the formula: time = distance / speed.

The speed of the ferry is given as 9 km/h, and the speed of the river current is given as 1 km/h. Since the ferry is traveling downstream, we need to add the speed of the river current to the speed of the ferry to get the effective speed.

The effective speed of the ferry is 9 km/h + 1 km/h = 10 km/h.

Now we can calculate the time it will take for the ferry to travel 90 km downstream using the formula:

time = distance / speed

Substituting the values, we get:

time = 90 km / 10 km/h = 9 hours

Therefore, the correct answer is а). 9 hours.

Answer

The ferry will take 9 hours to travel 90 km downstream. Therefore, the correct answer is а). 9 hours.