Mrs. Barojas walked to a copier in her office, made a copy...

Mrs. Barojas walked to a copier in her office, made a copy of her proposal, and sent the original to one of her customers. When Mrs. Barojas looked at her copy before filing it, she saw that the copy had been made at an $80 \%$ reduction. She needs her filing copy to be the same size as the original. What enlargement scale factor must she use on the first copy to make a second copy the same size as the original?

Transcript

00:01 All right, friends, let's talk through this situation.

00:02 So our keyword is dilation.

00:05 And so a dilation of a figure, a dilation of a figure is when the figure is enlarged or reduced by a certain scale factor.

00:14 Let's talk through these four quick examples and then we'll take a look at yours.

00:18 So it says an enlargement with a scale factor of two means the figure will have a 200 % increase.

00:25 This means the new figure will double the size of the original.

00:30 So doubling the size of the original is a 200 % increase.

00:34 So a reduction with a scale factor of 0 .5, so a number that is less than 100 % or less than 1, means the figure will have a 50 % decrease.

00:45 This means the new figure will be half as large as the original.

00:50 Now, our next situation is another enlargement.

00:53 So it says an enlargement with a scale factor of 0 .3 means the figure will have a 30 % increase to our figure.

01:03 Now, the other way we can write this, sometimes you will see this as a 130 % increase because it's going to be bigger than 1.

01:11 So it would be 0 .13.

01:13 That's another way that you may see that depending on how your textbook is worded.

01:17 This means the new figure will be 30 % larger or 130 % of the original.

01:23 A reduction with a scale factor of 0 .4 means the figure will decrease by 40%.

01:30 This means the figure will be 60 % of the original...

Question

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