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Algebraic Expressions Videos 17 videos

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SAT Math 2.2 Numbers and Operations 215 Views


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SAT Math 2.2 Numbers and Operations. According to the information given, how many times faster is Car A than Car D?


Transcript

00:02

Time for your daily dose of Shmoop. So open wide.

00:06

According to the information given below, how many times faster is Car A than Car D?

00:11

Car A is twice as fast as B.

00:14

Car B is three times as fast as C.

00:16

Car C is twice as fast as D.

00:18

And Car D is half as fast as C.

00:21

And here are the potential answers:

00:25

So this is a bake-your-own-algebraic-equation kind of problem.

00:29

It says that car A is twice as fast as car B… so we can write A equals 2B…

00:33

Car B is three times as fast as Car C so B = 3C…

00:37

Car C is twice as fast as Car D so C = 2D…

00:42

Car D is half as fast as Car C so D = 1/2C…

00:46

…and Cars 2 is half as good as The Incredibles.

00:51

Okay, now we just have to simplify.

00:53

Let's just connect everything that we know B equals…

00:56

B = 3C = 3(2D) = 6D.

01:02

It takes 6 D’s to make one B. 

01:04

But the question is asking us to compare A with D…

01:06

so we somehow need to map B onto A.

01:09

We know that it takes 2 B’s to make an A. So if it takes 6 D's to make one B, then it

01:14

should take 2 times 6 D's to make an A… or 12 D's.

01:18

Answer E.

01:19

So car A is like a Ferrari and car D is like your portly grandpa’s lawnmower.

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