ShmoopTube

00:04

And here's your shmoop du jour...

00:07

Ever since Tango spotted Daisy, he's been newly motivated to get in shape.

00:11

He's made no such resolution about quitting, the practice of scratching his butt in public though.

00:16

Baby steps.

00:18

After joining the monkey gym and eating healthier, Tango has seen his weight go from 180 to 155 pounds.

00:24

This is a decrease of, approximately, what percent?

00:28

And here are the potential answers...

00:33

Ok, what is this problem testing?

00:36

Our ability to recognize that it's a problem involving RATE OF GROWTH ...

00:40

or, rate of shrinkage in Tango's case here.

00:44

So we'll need the rate of growth formula, which is new minus old over old.

00:52

Also note the curveball -- the question is asking for the DECREASE in weight.

00:56

Had it asked for the CHANGE in weight, we'd have to think about whether the answer is

00:59

a positive or negative number...

01:01

...but note in the question set they are all positive, so at least we don't have to worry

01:06

about positives and negatives in this problem.

01:09

To answer, we just plug in the key terms.

01:11

For the NEW weight we look to Tango and his now svelte figure; he weighs in at 155 pounds.

01:18

A big improvement from his former, hefty weight of 180 pounds.

01:22

So new minus old over old gets us 155 minus 180 over 180...

01:28

...which boils down to 25 over 180, which reduces further to 5 over 36.

01:36

Now just some careful long division to calculate the percentage and we're there.

01:42

36 goes into 5... to get us roughly 14%.

01:46

As in all of these types of questions, this is the BEST answer, not the PERFECT answer.

01:50

Which is just fine... as Daisy isn't really looking for perfect.

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