Question

Satellite73, could you please help me?youre the only one thats good at this precalc stuff lol

Answer 1

Or anyone thats good at it, please? :(

Answer 2

what do you need help with.

Answer 3

specifically

Answer 4

Use the exponential model P=54.7e ^.19t to determine when P=123.68. Then convert to base b

Answer 5

that is easy

123.68/54.7 = e^(.19t)
=
ln(123.68/54.7) = .19t
t = ln(123.68/54.7)/.19

Answer 6

stuff with exponential growth and decay models.

Answer 7

I posted somme other ones that people didnt know how to answer:?can you look at them?

Answer 8

I guess..

Answer 9

can you just post the questions in this thread you need help with specifically

Answer 10

In 1990, the population of africa was 643 million and by 2000 it had grown to 813 million. Write an exponential model in base b for the population of africa t after 1990. What is the annual percent increase?

Answer 11

so we use the exponential model 813=643e^(10*r)
we are trying to find the rate

so do what I did before with this equation
813=643e^(10*r)
813/643 = e^(10r)
ln(813/643) = 10r
ln(813/643)/10 = r

here are some lecture notes that cover exponential functions and the type of questions that you are covering

Answer 12

yeah i have a bunch of notes, i jst dont understand it

Answer 13

When you read the question just right down all the variables that it gives you
you know the intiial population is
n = 643
Principle = 813
Time = 10 years (2000 - 1990)
and you should know the formula
P(t) = ne^(tr)

Answer 14

what are you not getting?

Answer 15

i just did the calculations for that one and i got .02345, and that doesnt seem right at all

Answer 16

which one?

Answer 17

the africa population one

Answer 18

its right, I just checked

Answer 19

the population is increasing exponentially by 2%.

Answer 20

then what is the model for it?

Answer 21

You can check by inserting .023 into r in the equation
643e^(10*0.023) = 813

Answer 22

You are modeling for population growth, so you are finding at what percent exponentially the population increased, with that rate you can insert 20 for t and know how people in africa starting with 643million will be in africa after 20 years

Answer 23

but it doesnt make sence that its only 2 percent when it went from 643, to 813, that seems like a higher percentage for everyyear increase

Answer 24

yes it does it is an exponential function. Look at the graph e^(x)

Answer 25

5^(5)
=
(5)(5)(5)(5)(5)
=
(25)(5)(5)(5)
125(5)(5)
625(5)
=
3125
see how large this number got

Answer 26

well then the second part of that question is write an exponential model in base e for the popul;ation of afrca t years after 1990 . what is the continuous annual increse?

Answer 27

Just multiply .023 by 100 to convert it to percent, thus 2.3 percent increase each year

Answer 28

butfor continuously, its a different equation

Answer 29

is that the full question?

Answer 30

ehi dont even know, i have a feeling were getting all this wrong

Answer 31

No the last two questions are right but you don't have to believe me

Answer 32

i dont know, continuously is a different equation though let me find it

Answer 33

its the pe^rt formula

Answer 34

that is the formula I used before...

Answer 35

only I formated it P=ne^(rt)

Answer 36

but thats only for continuouslyt

Answer 37

Are they just tell you to state the function? because I already did that
643e^(t*0.023) =P(t)

Answer 38

If you graphed that function it would show you how the african population increases over the years after 1990

Answer 39

it tells me to put the model, and the percent increase on both base e and base b

Answer 40

can I see the question?