Let P(t) persons have heard after t hours, where P(t) = ....

caitfrawley66

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In a particular town a population A, 20 percent of the residents heard a radio announcement about a local political scandal on their way to work at 7:00 a.m. If 50 percent of the population had heard about the scandal by 8:00 a.m., what time was it when 80 percent of the population had heard about it?

Let P(t) persons hear about the scandal after t hours, where P(t) = A / ( 1 + Be-Akt)

Note: The "-Akt" is the power on e.
 
Re: precal

caitfrawley66 said:
. In a particular town a population A, 20 percent of the residents heard a radio announcement about a local political scandal on their way to work at 7:00 a.m. If 50 percent of the population had heard about the scandal by 8:00 a.m., what time was it when 80 percent of the population had heard about it?

let P(t) persons hear about the scandal after t hours, where P(t)= A/( 1+Be-Akt)

the -Akt are exponents of e
Plug-n-chug.

P(t) = A/( 1+Be^-Akt) - "t" is hours

P(0) = A/( 1+Be^-Ak(0)) = 20

P(1) = A/( 1+Be^-Ak(1)) = 50

Find

P(t0) = A/( 1+Be^-Ak(t0)) = 80

You've three parameters and only two clues, so something magic will have to occur.
 
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