Question

i need help with exponential growth please ..
medal and fan!

Answer 1

so i know that every 7 years they make 2 million..

Answer 2

this doesn't really help you, it is not linear

Answer 3

i dont use the formula..

Answer 4

30/28≈ 1.0714
So in 7 years the exponential growth is 1.0714.
So, next time it will grow 1.0714 exponentially from 30 million (starting from year 1999, till year 2008)

Answer 5

no it is more than 7 years, hold..

Answer 6

you should divide the exponent by 7 to get the additional growth
1/07 ÷ 0.15
So the common ratio is 1.014 ( I think)
lets check this
28 times 1.015^6 = 30.6164113904

Answer 7

yep, and you got 9 more years from 30 million, so

30 million, × 1.015^(9-1) ----> =33794777.5979

Answer 8

I will leave the estimation to you.

Answer 9

method two
use the exponent of \(\frac{t}{7}\) and keep the rate \(\frac{30}{28}\)

Answer 10

i dont get it.. usually i estimate how much per year then add them up to get to the current year

Answer 11

that does not work because population growth is not "linear"
it grows proportionally to the amount present
i.e. it is exponential

Answer 12

simple example
if a population starts at 3 and doubles every two years, it two years it will be 6, but in another two years it will be 12, not 9

Answer 13

i solved it like that before.. with this one http://assets.openstudy.com/updates/attachments/53f12a78e4b0f30a87d981ca-joftheworld-1408315802315-screenshot20140817at6.50.04pm.png

Answer 14

we can do that too, i takes more work, but it is doable

Answer 15

so how else would i do it ?

Answer 16

easiier to use only the numbers given
\[P(t)=28\times \left(\frac{30}{28}\right)^{\frac{t}{7}}\] where\(t\) is years after 1992

Answer 17

oh you're using the formula \[P=Ae ^{kt}\]

Answer 18

no

Answer 19

i dont get it ..

Answer 20

@KlOwNlOvE

Answer 21

id solve this using
\[A=P(1+r)^{t}\]

Answer 22

but i dont understand it that way..

Answer 23

A will be the number you're solving for
P is your starting point
R is the rate that it's changing a
and T is the time

Answer 24

whats the rate of change?

Answer 25

per year

Answer 26

2 million every 7 years?

Answer 27

yes thats for every 7 years and we need per year so
\[2,000,000\div7=?\]

Answer 28

285.71

Answer 29

ok and we are solving for how many years after 1999?

Answer 30

2008-1999=?

Answer 31

9 years..?

Answer 32

yes lets plug in our numbers now starting at 28
\[A=28(1+285.71)^{9}\]

Answer 33

\[A=28(286.71)^9\]

Answer 34

3.58 ?

Answer 35

I think i did something wrong
we could do
30000000+(285.71*9)?

Answer 36

whered you get 300 million ??

Answer 37

id go with the way solo solved it more exact

Answer 38

thats 30million not 300

Answer 39

this is confusing ...