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SAT Diagnostic #2 189 Views


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Description:

SAT Diagnostic #2

Language:
English Language

Transcript

00:03

Algebra and functions: world problem a'la shmoop

00:07

Lance rode his bike to school pedaling at an average speed of 12 miles per hour. [Lance riding his bike to school]

00:13

When he rode his bike back home at a leisurely pace of 10 miles per hour, it took him an

00:18

extra 15 minutes.

00:20

So..how far is his school from his home?

00:24

And here are the potential answers…

00:25

As you know, a full day of school can really sap your energy. [Tired boy sleeping after a exhausting day at school]

00:30

So it’s no surprise that Lance is draggin’ a bit on the way home.

00:34

This question is asking about the difference that those 2 miles an hour make… [Road leading from school to lance's home]

00:38

…since they lost Lance an extra 15 minutes.

00:41

Time that could have been well spent doing math homework. [Boy doing math homework]

00:44

Okay, formula time.

00:45

There's a basic equality here – since Lance is traveling the same distance both ways. [Lance travelling down a road from home to his school and riding back]

00:51

It's just taking him a little longer on the way back home.

00:53

Pick up the pace, boy…

00:56

All right…so let’s call the 12 miles per hour average Lance took to get to school “12x”…

01:01

…and the time it took him to get home “10x + 0.25”.

01:07

The 10x represents his average speed on the way home…

01:11

… and the “0.25” represents the extra quarter of an hour it takes him to pedal his [clock ticking by]

01:15

way home.

01:16

Because Lance is traveling an equal distance both times, we can say that 12x = 10x + 2.5.

01:25

Take away 10x from both sides…

01:28

And we get 2x = 2.5.

01:30

Divide both sides by 2 and we have a value for our “x”…1.25 hours. [2x and 0.25 divided by 2]

01:35

That’s nice and all… but we’re solving for distance. [Boy shrugging his shoulders at math equations]

01:40

So we still have to multiply the time by Lance’s average speed.

01:43

We take 1.25 hours multiplied by 12 miles per hour which gives us our final answer…15

01:50

miles.

01:51

Looks like the answer is option E – Lance has a 15 mile ride to and from school. [Lance cycles across the screen]

01:57

Sheesh.

01:58

We get tired driving our car for 15 miles… [Man falling asleep on his steering wheel]

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