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Functions Videos 43 videos

Piecewise Functions
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Don’t even think about starting up your combo lemonade/fro-yo stand without first making sure you understand piecewise functions. You’re just a...

Domain and Range
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Domain and range: two terms you will learn to love (or hate with a vengeance). The domain is the set of all possible x values, and range is the set...

Functions as Models
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Functions briefly flirted with the idea of being infomercial hosts, but they didn’t shine when talking on-camera. They’re much better off in th...

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SAT Math 1.2 Algebra and Functions 359 Views


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Description:

SAT Math: Algebra and Functions Drill 1, Problem 2. Based on the data in the table, what is the maximum heart rate for the average 22-year-old?

Language:
English Language

Transcript

00:02

And we're getting math-y with it...

00:04

The table below gives the average maximum heart rate,

00:07

by age, for a person exercising at full effort.

00:11

Based on the data in the table,

00:13

what is the maximum heart rate for the average 22-year-old?

00:17

And here are your possible answers...

00:21

If we look at the data, as age increases by 5, average max heart rate decreases by 5.

00:28

Since age acts as our independent variable and average max

00:32

heart rate acts as our dependent variable,

00:38

we can calculate the change in average heart rate over age as the slope of our equation.

00:44

Which gives us negative 1.

00:46

The point slope form of a linear equation is y minus y1 equals slope times x minus x1.

00:54

h is y in this situation because it's the dependent variable, and a is x in this situation

01:01

because it's the independent variable.

01:04

We can take any x1 and y1 point to plug into the point-slope form of the equation...so

01:10

let's just take the points 20, 200.

01:13

We get h - 200 = -1(a - 20).

01:18

H minus 200 equals negative a plus 20.

01:22

Adding 200 to both sides of the equation... we have h equals 220 minus a.

01:27

We're looking for h given that a equals 22 years old.. so we get that h equals 198.

01:34

Answer's E.

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