ShmoopTube

00:02

Here's a shmoopy question...

00:05

Karen is running away from the zombies who are pursuing her.

00:08

She can run two-thirds of a mile in five minutes.

00:11

At this rate, how many miles can she run in 12.5 minutes?

00:15

And here are the potential answers.

00:18

Before we spoil the ending, hit pause and try it yourself.

00:21

OK, this problem is asking about rates, time and distance.

00:25

We have to apply the ratio and figure out the function.

00:28

And assume that Karen has great endurance. So to solve we just set up a ratio.

00:33

We have two thirds of a mile in 5 minutes.

00:36

Assuming there is no degradation in speed over the longer distance...

00:39

...then we have a ratio of 2 over 15 miles in 1 minute.

00:43

In case you missed that, we just did 2/3 divided by 5, to get 2 over 15.

00:51

To find out how many miles she can run in 12.5 minutes, we can just multiply 2 over 15 times 12.5.

00:58

Let's convert 12.5 into a fraction so that it's easier to multiply fractions.

01:03

12.5 converts to 25 over 2... so 25 over 2 times 2 over 15.

01:11

The 2's cancel out, so we have 25 over 15, or five-third miles.

01:17

Convert our improper fraction to a mixed number, and we have 1 and two-third miles.

01:22

Looks like our answer is B.

01:24

Now that's using our brains.

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