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SAT Math 8.4 Geometry and Measurement 327 Views


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SAT Math 8.4 Geometry and Measurement

Language:
English Language

Transcript

00:03

Here’s your shmoop du jour, brought to you by shadows.

00:06

Peter Pan is offering a $500 reward for his, in case you see it.

00:11

A person 5 ft. 10 in. tall casts a shadow 10 ft. 2 in. long.

00:17

Approximately how tall is a tree that casts a 15 ft. 6 in. shadow?

00:24

Here are the potential answers...

00:29

Okay, we’ve got one fella whose shadow is nearly twice as long as he is tall.

00:34

So, now in roughly the same spot…

00:37

…is a tree whose shadow has got our hero’s shadow beat by over 5 feet.

00:42

And we want to figure out… how tall is this tree?

00:44

Well, what we have here is a simple ratio.

00:47

The person’s five feet and 10 inches is to his 10 foot, 2 inch long shadow…

00:52

…as “x” is to the tree’s 15 foot, 6 inch shadow.

00:57

This problem is going to be a heck of a lot easier to deal with if we convert everything

01:00

to inches, so…let’s do that.

01:03

70 inches is to 122 inches…

01:05

…as x is to 186 inches. We’ll set everything up as a fraction…

01:11

70/122 = x/186…

01:15

…and now we can just cross-multiply.

01:17

122x = 13,020

01:20

Divide both sides by 122 and x = 106.72.

01:26

Now, remember…we converted everything to inches, so now we have to convert back to feet.

01:31

106.72 divided by 12 is 8.89 feet…

01:34

…which is option C.

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