Question

Катер проплыл расстояние 84 км за 3 ч, после чего ему осталось проплыть 140 км. За сколько времени он проплывет оставшееся расстояние , увеличить скорость на 7 км\ч

Answer 1

84:3=28(км/ч) скорость катера в первые 3 часа
28+7=35(км/ч) увеличенная скорость катера
140:35=4(час.) 

ответ : за 4 часа катер проплывет оставшиеся 140 километров.

Answer 2

84:3=28 км/ч
28+7=35 км/ч
140:35=4 часа. 
Ответ: за 4 часа проплывет катер, если увеличит скорость. 

Answer 3

Problem Analysis

We are given that a boat has already traveled a distance of 84 km in 3 hours. The boat needs to cover an additional distance of 140 km. We are asked to find the time it will take for the boat to cover the remaining distance if its speed is increased by 7 km/h.

Solution

To find the time it will take for the boat to cover the remaining distance, we need to calculate the speed of the boat after it increases by 7 km/h. Then we can use the formula `time = distance / speed` to find the time.

Let's calculate the speed of the boat after the increase: - Initial speed: Unknown - Initial distance: 84 km - Initial time: 3 hours - Final distance: 140 km - Final speed: Unknown

We can set up the following equation using the formula `speed = distance / time`: `(84 km + 140 km) / (3 hours + time) = (84 km + 140 km) / (3 hours) + 7 km/h`

Simplifying the equation: `(224 km) / (3 hours + time) = (224 km) / (3 hours) + 7 km/h`

To solve for `time`, we can cross-multiply and solve the resulting equation.

Let's calculate the value of `time` using the given information.

Calculation

`(224 km) / (3 hours + time) = (224 km) / (3 hours) + 7 km/h`

Cross-multiplying: `(224 km) * (3 hours) + (224 km) * (time) = (224 km) * (3 hours + time) + (7 km/h) * (3 hours)`

Simplifying: `672 km * hours + 224 km * time = 672 km * hours + 224 km * time + 21 km * hours`

Canceling out the common terms: `224 km * time = 21 km * hours`

Dividing both sides by `224 km`: `time = (21 km * hours) / (224 km)`

Simplifying: `time = 0.09375 hours`

Converting hours to minutes: `time = 0.09375 hours * 60 minutes/hour = 5.625 minutes`

Therefore, it will take the boat approximately 5.625 minutes to cover the remaining distance when its speed is increased by 7 km/h.

Answer

The boat will take approximately 5.625 minutes to cover the remaining distance when its speed is increased by 7 km/h.