Question

In 1980 median family income was about$16,000, and in 2000 it was bout $40,000.
(a) find the slope of the line passing through points 1980,16000 and (2000,40000).
(b) Interpret the slope rate of change.
(c) If this trend continues, estimate the median family income in 2006

Answer 1

Do you know the formula for slope?

Answer 2

let y2-y1 over x2-y2

Answer 3

and divide by 3

Answer 4

\[M=y _{2}-y_{1}/x_{2}-x_{1}\]

Answer 5

yes

Answer 6

Alright, your two points are (1980, 16000) and (2000, 40000) whats the slope?

Answer 7

the slope do i subtract 40,000 from 16,000

Answer 8

and divide by 3

Answer 9

No there is no dividing by 3, use the slope formula

Answer 10

well you have to subtract the two top numbers and the instructions says divide by 3

Answer 11

i am going to look again to see what two numbers for the slope

Answer 12

You do 40000-16000/2000-1980

Answer 13

ok i got to calculate

Answer 14

24,000/20

Answer 15

Which is 1200

Answer 16

yes i got that too

Answer 17

Alright do you know how to do point-slope form?

Answer 18

i believe the family rate decreases by 12,000 between 1980-2000

Answer 19

No, the median family income increased by 24000 between 1980 and 2000.

When it says to interpret the slope that means to say what it means in the context of this problem. It means every year the median income increases by $1200

Answer 20

oh ok i see so the family income of 12,000 will increase in 2006

Answer 21

silly me thank you

Answer 22

Wait, for part c we have to do something else

Answer 23

ok

Answer 24

this is the formula we use to get an equation that we can use to estimate the income in 2006.

\[y-y _{1}=m(x-x _{1})\]

Answer 25

SO WEHAVE TO FIND THE FAMILY INCOME FOR 2006

Answer 26

So which point do you want to use to plug into the formula

Answer 27

SO THE M=12000 ON HERE?

Answer 28

no 1,200. you added a 0

Answer 29

Do you want to use the point (1980, 16000)?

Answer 30

16,000-12,000

Answer 31

when we plug everything in, itll look like

y-16000=1200(x-1980)

Answer 32

Y-16000=12000X-23760000 i think this is wrong but i multiplied12000 into whats in the brackets

Answer 33

No thats what you do first, but you keep adding a 0. the slope is 1,200, not 12,000

Answer 34

y-16000=1200x-237600

Answer 35

You keep forgetting or adding zeros.
y-16000=1200x-2376000

Answer 36

ok well i think im not getting this second part

Answer 37

You have the right idea you just keep adding or forgetting zeros.

after we get that we subtract 16000 from both sides

Answer 38

ok subtract 16000 and after i divide

Answer 39

Im sorry, add 16000, not subtract.

you end up with:
y=1200x-2360000

Answer 40

where x stands for the year and y stands for the median income.
What would you plug in for x since you want to find the income for 2006?

Answer 41

oh ok add 16000 because it is already a negative so change to add

Answer 42

Yep so if you want to find the income for 2006, what do you plug in for x?

Answer 43

y=1200(20)-2360000

Answer 44

2000-1980=20

Answer 45

x=20

Answer 46

No, x represents the year, if you want to find the income for 2006, you plug in 2006 for x.

y=1200(2006)-2360000

Answer 47

ok i calculate now for answer

Answer 48

47,200

Answer 49

Thats correct

Answer 50

omg this is hard

Answer 51

Well now you're all done =D

Answer 52

thanks i guess its hard with my infant aggravating me thank u