Question

Срочно!!!!!!помогите!!!!расстояние между двумя пристанями на реке 32,4 км. за сколько времени катер проплывет этот путь и вернется обратно, если собственная скорость катера 18 км/ч , а скорость течения реки на 80% меньше скорости катера

Answer 1

18*80:100=14,4км/ч скорость реки
18+14,4=3,6км/ч
18+3,6=21,6км/ч по течению
18-3,6=14,4км/ч против течения
32,4:21,6=1,5 час
32,4:14,4=2,25 часа
1,5+2,25=3,75 часа

Answer 2

Calculation of Time Taken by the Boat

To calculate the time taken by the boat to travel the distance between the two piers and return, we need to consider the boat's speed and the speed of the river current.

Given: - Distance between the piers: 32.4 km - Boat's speed: 18 km/h - River current speed: 80% less than the boat's speed

To calculate the time taken by the boat, we need to determine the effective speed of the boat, taking into account the river current.

Let's calculate the effective speed of the boat first:

Effective speed of the boat = Boat's speed - (River current speed)

Given that the river current speed is 80% less than the boat's speed, we can calculate the river current speed as follows:

River current speed = 80% of the boat's speed

Now we can calculate the effective speed of the boat:

Effective speed of the boat = Boat's speed - (0.8 * Boat's speed)

Simplifying the equation:

Effective speed of the boat = 0.2 * Boat's speed

Substituting the given value of the boat's speed (18 km/h):

Effective speed of the boat = 0.2 * 18 km/h = 3.6 km/h

Now that we have the effective speed of the boat, we can calculate the time taken by the boat to travel the distance between the piers and return.

Time taken = Distance / Effective speed of the boat

Substituting the given distance (32.4 km) and the effective speed of the boat (3.6 km/h):

Time taken = 32.4 km / 3.6 km/h

Calculating the time taken:

Time taken = 9 hours

Therefore, the boat will take 9 hours to travel the distance between the two piers and return.