Question

Катер идет от одной пристани к другой со скоростью 30 км/ч, а возвращается обратно со скоростью на 10 км/ч большей. За какое время катер пройдет весь путь туда и обратно, если расстояние между пристанями 240 км? ​

Answer 1

Ответ:

14

Пошаговое объяснение:

240:30=8ч

240:(30+10)=6ч

8+6=14ч

Answer 2

1)30+10=40(км/ч)-скорость катера по возвращению назад

2)240:30=8(ч)- время к одной пристани ко второй

3)240:40=6(ч)-на обратный путь

4)8+6=14(ч)-нужно

Ответ:14 часов

запомни как решать такие задачки

Answer 3

Problem Analysis

We are given that a boat travels from one dock to another at a speed of 30 km/h and returns at a speed that is 10 km/h faster. We need to find the total time it takes for the boat to complete the round trip, given that the distance between the docks is 240 km.

Solution

To find the total time for the round trip, we can divide the total distance traveled by the average speed of the boat. The average speed can be calculated by taking the harmonic mean of the two speeds.

Let's calculate the average speed first: - Speed of the boat while going = 30 km/h - Speed of the boat while returning = 30 km/h + 10 km/h = 40 km/h

The average speed, v_avg, can be calculated using the formula:

v_avg = 2 * v1 * v2 / (v1 + v2)

where v1 and v2 are the speeds of the boat while going and returning, respectively.

Substituting the values, we get:

v_avg = 2 * 30 * 40 / (30 + 40) = 2400 / 70 = 34.2857 km/h

Now, we can calculate the total time, t_total, using the formula:

t_total = distance / v_avg

Substituting the values, we get:

t_total = 240 km / 34.2857 km/h = 7 hours

Therefore, the boat will take 7 hours to complete the round trip.

Answer

The boat will take 7 hours to complete the round trip.

Explanation

The boat travels from one dock to another at a speed of 30 km/h and returns at a speed that is 10 km/h faster. The average speed of the boat is calculated using the harmonic mean of the two speeds, which is approximately 34.2857 km/h. The total distance between the docks is 240 km. Dividing the distance by the average speed gives us the total time for the round trip, which is 7 hours