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2 years ago

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Kelli swam upstream for some distance in one hour. She then swam downstream the same river for the same distance in only 6 minut

es. If the river flows at 5 km/hr, how fast can Kelli swim in still water?
Choose the most logical value for the variable to represent.
Let x = .

3m = 15

9 + 15m = 12m – 1

3m = 18

9 + 6 – 15 = 15m – 12m

1 answer:

never [62]2 years ago

5 0

By solving a system of equations, we conclude that Kelli's speed on still water is 6.1km/h

<h3></h3><h3>How fast can Kelli swim in still water?</h3>

Let's say that the speed of Kelli in still water is S. And we know that the speed of the river is 5km/h.

When she swims upstream, her velocity is:

(S - 5km/h)

When she swims downstream, her velocity is:

(S + 5km/h)

With the given information, we can write for a distance D:

(S - 5km/h)*1h = D

(S + 5km/h)*6min = D

First, let's rewrite 6 minutes into hours.

1 hour = 60min

6 min = 6/(60) hours = 0.1 hours

Then the system of equations that we need to solve is:

(S - 5km/h)*1h = D

(S + 5km/h)*0.1h = D

D is the same distance in both cases, then we can write:

(S - 5km/h)*1h = (S + 5km/h)*0.1h

Now we can solve this for S.

S*1h - 5km = S*0.1h + 0.5km

S*1h - S*0.1h = 5km + 0.5km

S*(0.9h) = 5.5km

S = 5.5km/0.9h = 6.1km/h

Kelli's speed on still water is 6.1km/h

If you want to learn more about systems of equations:

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