Question

The percentage of automobile cunsumers who are under 50 years of age degreased linerly from 55.9% in 1990 to 52.4% in 2005. Predeict when the percentage will be 48%?

Answer 1

Just use the slope formula to get the slope, then use the point slope formula to find the equation

Answer 2

So, \[52.4-55.9/105-90\]?

Answer 3

yes, that's a good start.

Answer 4

Well somewhere I'm getting hung up...so i end up with -3.5/15. Then go \[55.9=-3.5/15(90)+b? \]

Answer 5

if this is right, that's where I'm stuck. I now have to predict when it will be 48%? Plug 48 into y?
Solve

Answer 6

Wait a sec...

Answer 7

K :S

Answer 8

Sorry, I thought you were using the point slope form. You decided to do this the other way...

What do you get for b?

Answer 9

Well originally 76.9

Answer 10

That's correct

Answer 11

So what is your y = mx + b formula now?

Answer 12

Should i plug the 48 in as y?

Answer 13

yes

Answer 14

\[48=-3.5/15x+76.9\]
Solve for x

Answer 15

yes,and what do you get for x?

Answer 16

-26.57?

Answer 17

I get year 2023 and 10.2/12 months

Answer 18

Hmm...so first I -76.9 from both sides?

Answer 19

so right around October of year 2023

Answer 20

Yes correct

Answer 21

End up with -28.9 = -3.5/15x

Answer 22

yes

Answer 23

Do I convert m to -2.33?

Answer 24

wait a sec...

Answer 25

You should just solve it without converting.

Answer 26

So did you get 433.5/3.5?

Answer 27

123.86

Answer 28

So in years 1900 + 123.6 = 2023.6?
That seems a lot close to what you had

Answer 29

Close enough. Good job

Answer 30

Wow...what a pain. OK, well thank you for the time. That is a lot closer to a realistic answer. Just need to make sure I follow each step carefully. Thanks again.