Question

Fan or Medal
The equation, y = 12841(1.01)x , represents the average cost of an education at a private college, after 1990. What is the average cost in 1990 (x = 0)?
$12,969
$12,841
$13,122
$13,099

Answer 1

12841, because 1 year after 1990, the avg tuition would be 12,969

Answer 2

you plug in x = 0 and evaluate to get your answer

Answer 3

12969.41??

Answer 4

12969.41 is the average tuition after 1 year

Answer 5

in 1990 it's simply going to be 12841

Answer 6

no

Answer 7

y is the average cost each year

Answer 8

so you just plug in x = 0 and you evaluate

Answer 9

but then dont you get 0?

Answer 10

the equation is

y = 12841(1.01)^x

the symbol ^ didn't make it when it was pasted

Answer 11

oh! lol ok

Answer 12

cost is usually modeled by exponential functions

Answer 13

can one of you draw a example?

Answer 14

@jim_thompson5910 @blurbendy

Answer 15

exponential functions look like this

Answer 16

ie the cost grows at a slow rate at first, but that growth rate increases over time

Answer 17

I understand that but how do you work the problem and why do you put your number where you put them @jim_thompson5910

Answer 18

y = 12841(1.01)^x

y = 12841(1.01)^0 ... plug in x = 0

y = 12841(1)

y = 12841

Answer 19

so that's all there is to it really

Answer 20

okay this is not part of the question but what if x=50?? @jim_thompson5910

Answer 21

plug in x = 50 and evaluate

Answer 22

tell me what you get

Answer 23

how would I mutilpy out x, do I do it like a expont or do I just times it or what do I do is my question really? @jim_thompson5910

Answer 24

you use a calculator, so

y = 12841(1.01)^x

y = 12841(1.01)^(50) ... plug in x = 50

y = 12841(1.64463182184389) ... use a calculator

y = 21,118.7172242973 ... use a calculator

y = 21,118.72 ... round to the nearest penny

Answer 25

so the average cost goes from $12,841 in 1990 to $21,118.72 in 2040 (50 years later)

Answer 26

make sense?

Answer 27

yea okay so what if they give me the Y but not the x? how do I work this one?

Answer 28

you plug in the given value for y, then solve for x

Answer 29

you would use logs to do so

Answer 30

how would I slove for x, if you don't mind please show me the way you did step by step I understood that better

Answer 31

what value of y are they giving you?

Answer 32

they didn't give me one but we can use 11 or just choose a number

Answer 33

so why do you want to solve for something they didn't give you?

Answer 34

so I know how to work it when it comes time?

Answer 35

are they asking you to solve for x? without giving the value of y

Answer 36

i gotcha

Answer 37

ok pick any cost value between 10 thousand and 20 thousand

Answer 38

11,356 is that okay?

Answer 39

sure