Answer
$56$ years old.
Work Step by Step
Let $P(x)=70$; we have
$\frac{90}{1+271e^{-0.122x}}=70$
and
$271e^{-0.122x}=\frac{90}{70}-1\approx0.2857$
Thus
$x=-\frac{ln(0.2857/271)}{0.122}\approx56$ years old.
Precalculus (6th Edition) Blitzer
by Blitzer, Robert F.
Published by
Pearson
ISBN 10:
0-13446-914-3
ISBN 13:
978-0-13446-914-0
Chapter 3 - Section 3.5 - Exponential Growth and Decay; Modeling Data - Exercise Set - Page 507: 46
Update this answer!
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.
