Question

Моторная лодка проехала 36 км вниз по реке со скоростью 18км/ч.Возвращяясь в отправочный пункт,её скорость была на 50 % меньше.Найдите среднюю скорость моторной лодки в этом пути.

Answer 1

18+9=27
27/2=13.5
0000000000000000000

Answer 2

Calculation of Average Speed

To find the average speed of the motorboat on its round trip, we need to consider the speed of the boat during the downstream and upstream portions of the journey.

Let's break down the problem step by step:

1. The motorboat traveled downstream for 36 km with a speed of 18 km/h. 2. On the return journey, the boat's speed was 50% less than its original speed.

To calculate the average speed, we can use the formula:

Average Speed = Total Distance / Total Time

To find the total distance, we need to consider the distance traveled downstream and the distance traveled upstream.

Let's calculate the total distance:

1. Distance traveled downstream = 36 km 2. Distance traveled upstream = 36 km

The total distance is the sum of the distances traveled downstream and upstream:

Total Distance = Distance Downstream + Distance Upstream

Total Distance = 36 km + 36 km = 72 km

Now, let's calculate the total time:

1. Time taken to travel downstream = Distance Downstream / Speed Downstream - Speed Downstream = 18 km/h - Time Downstream = 36 km / 18 km/h = 2 hours

2. Time taken to travel upstream = Distance Upstream / Speed Upstream - Speed Upstream = 50% less than the original speed = 0.5 * 18 km/h = 9 km/h - Time Upstream = 36 km / 9 km/h = 4 hours

The total time is the sum of the time taken downstream and upstream:

Total Time = Time Downstream + Time Upstream

Total Time = 2 hours + 4 hours = 6 hours

Now, we can calculate the average speed:

Average Speed = Total Distance / Total Time

Average Speed = 72 km / 6 hours = 12 km/h

Therefore, the average speed of the motorboat on this trip is 12 km/h.