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SAT Math 1.1 Algebra and Functions 315 Views


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Description:

SAT Math 1.1 Algebra and Functions. Find an algebraic equation to correspond with the data.

Language:
English Language

Transcript

00:02

And we're getting mathy with it.

00:04

The table below gives the average maximum heart rate, by age, for a person exercising at full effort.

00:10

(Heart rate is in beats/min.)

00:13

Find an algebraic equation to correspond with the data.

00:16

Use a for age and h for heart rate.

00:19

And here are your possible answers...

00:23

Okay, if we look at the data…

00:25

as age increases by 5, average max heart rate decreases by 5.

00:31

Since age acts as our independent variable and average max heart rate acts as our dependent variable,

00:42

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

00:48

Which gives us negative 1. That's the slope.

00:51

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

00:58

And you should get that there are 2 points we’re thinking through here…

01:01

...that’s (x, y) and (x1, y1). h is y in this situation because it's the

01:06

dependent variable, and a is x in this situation because it's the independent variable.

01:12

We can take any x1 and y1 points... so let's just take the points 20 and 200.

01:18

Plugging into the equation with these numbers then, we get... h - 200 = -1(a - 20).

01:25

h minus 200 equals negative a plus 20.

01:28

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

01:34

Let's make sure this equation checks out with the data in the table....

01:37

Let’s plug in age 45 and see if the end answer is right.

01:42

Plugging in a equals 45...

01:44

h = 220 - 45, so that's 175.

01:49

Check it here on the table and yup, it checks out!

01:51

So our equation is h equals 220 minus a.

01:56

Answer A is our guy!

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