Question

Between 1960 and 1990 the population of a
town increased at rate of 0.16% per year. The
population P is given by
P = 1455 · (1.0016)t
where t = 0 corresponds to 1980.
Find the population of the town in
a. 1960..

So i started off by using the formula above but each time I enter it I get it wrong.

Answer 1

whats wrong?

Answer 2

t = the time since 1980

Answer 3

t=20

Answer 4

you want 20 years in the past

Answer 5

moving Left on the x axis , negative

Answer 6

t = -20

Answer 7

But according to that equation, the population is Zero in 1980 then t = 0

Answer 8

sure its not an exponential function?

Answer 9

is P=1445+1445*(.0016)t

Answer 10

so it means that in 1980 P was 1445

Answer 11

sure it is not P = 1455*(1.0016)^t

Answer 12

Yes thats how it is

Answer 13

ok so let t = -20 and find P

Answer 14

\[P = \frac{ 1455 }{ 1.0016^{20} }\]

Answer 15

I got 1502

Answer 16

i got 1409.21

Answer 17

remember it will be LESS people than in 1980

Answer 18

?

Answer 19

ohhhh

Answer 20

1455 / (1.0016)^20

Answer 21

Twenty years in the past, will be a negative exponent, you can move it to the denominatior

Answer 22

positive 20
I entered a negative
So now I got what you got

Answer 23

I confused
is the question 1455*(1.0016)^t???

Answer 24

yes

Answer 25

:)

Answer 26

Populatioin growth is exponential function

Answer 27

Logistic function really

Answer 28

So to find
1970 I would use t=10

Answer 29

t = -10

Answer 30

Which Is 1431

Answer 31

P = 1455(1.0016)^-10 = 1455 / (1.0016)^10

Answer 32

correct

Answer 33

Oh okay
So to find
1990 it would be t=-10

Answer 34

t = +10, but if you move it to the denominator it will be -10

Answer 35

t = years since 1980

Answer 36

For 1990 t=-10

Answer 37

and for 1980 it's Just 1455

Answer 38

\[P(1990) = 1455(1.0016)^{+10} = \frac{ 1455 }{ 1.0016^{-10} }\]

Answer 39

Yes for 1980 t = 0, and a number to the zero power is 1

Answer 40

P(1980) = 1455(1)

Answer 41

This Is fantastic! I got it right and I get the concept!

Answer 42

awesome, if you graphed, 1455(1.0016)^t you will see the growth where t =0 is 1980

it is a curve.

Answer 43

y = 1455(1.0016)^x

Answer 44

cool

Answer 45

i got to go for a bit, if you want to fan me, ill be back in a little while