# It took a crew 80 minutes to row 3km upstream and back again. If the rate of flow of the stream was 3km/h, what was the rowing rate of the crew?

##### 1 Answer

#### Answer:

#### Explanation:

It is important to keep the units all the same.

As unit time for velocities is in hours:

Total time = 80 minutes

Given that distance 1 way is 3Km

Let rowing velocity be

Let time to row against current be

Let time to row with current be

Thus

Known: distance is velocity x time

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Thus

For 'with current'

For against current

But

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Consider that

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Compare to

The negative solution is not logical so

Rowing speed is: