Question

Теплоход по течению двигался со скоростью 18 км/ч, а против течения - со скоростью 12 км/ч. С какой средней скоростью теплоход прошел весь путь туда и обратно, если расстояние между двумя пристанями равно 8 км?

Answer 1

Средняя скорость = 15 Км ч

Answer 2

15км час так как скорость течения была 3 км в час, 18-12=6 6/=3

Answer 3

Calculating the Average Speed of the Boat

To calculate the average speed of the boat for the entire journey, we can use the formula: Average Speed = Total Distance / Total Time

First, let's calculate the time taken for the boat to travel upstream and downstream.

Time taken to travel upstream and downstream

The boat's speed while traveling downstream (with the current) is 18 km/h, and its speed while traveling upstream (against the current) is 12 km/h. The distance between the two piers is 8 km.

The time taken to travel downstream can be calculated using the formula: Time = Distance / Speed

For the downstream journey: Time Downstream = 8 km / 18 km/h

For the upstream journey: Time Upstream = 8 km / 12 km/h

Calculating the Total Time and Average Speed

The total time for the entire journey is the sum of the time taken for the downstream and upstream journeys.

Total Time = Time Downstream + Time Upstream

Now, we can calculate the average speed using the formula: Average Speed = Total Distance / Total Time

Let's calculate the total time and average speed based on the provided information.

Calculation

- Time Downstream = 8 km / 18 km/h = 0.444 hours - Time Upstream = 8 km / 12 km/h = 0.667 hours - Total Time = 0.444 hours + 0.667 hours = 1.111 hours - Average Speed = 8 km / 1.111 hours = 7.2 km/h

Therefore, the average speed of the boat for the entire journey (both downstream and upstream) is 7.2 km/h.