2. Some psychologists have said that the hours is given by f(t)= (a) How many facts are remembered after one hour? Solution: f(1) = 9990 = 10. 90 (b) What is the rate at which the number of facts remembered is changing after 1 hour? Solution: Let's compute the derivative of f: (99t-90) (90t)' (90t) (99t-90)' f' (t) So we get f'(1) == 81000 90t 99t-90 = (99t-90)² (99t-90) (90) (90t) (99) (99t-90)² 8910t8100 - 8910t (99t-90)² = -100. -8100 (99t-90)² (c) What is the rate it's changing after 10 hours? Solution: Using what we did in part b, f'(10): - -8100 (900)2 -0.01 (d) Why is the rate of change so much smaller after 10 hours, compared to 1 hour? Solution: After 10 hours one has probably forgotten most of the new facts, so they are ting them at a much slower rate.

Calculus For The Life Sciences
2nd Edition
ISBN:9780321964038
Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Chapter4: Calculating The Derivative
Section4.EA: Extended Application Managing Renewable Resources
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where did the 900^2 come from in part c? Please explain . Thank you

2. Some psychologists have said that the number of new facts a person can remember after
hours is given by
(a) How many facts are remembered after one hour?
90
Solution: f(1) = 99-90 = 10.
f' (t)
(b) What is the rate at which the number of facts remembered is changing after 1 hour?
Solution: Let's compute the derivative of f:
=
f(t) =
=
90t
99t - 90
=
(99t-90) (90t)' - (90t) (99t-90)'
(99t-90)²
(99t90) (90) - (90t) (99)
(99t-90)²
8910t8100 - 8910t
(99t – 90)²
-8100
(99t – 90)²
So we get f'(1) = -8100
81
= -100.
(c) What is the rate it's changing after 10 hours?
Solution:Using what we did in part b, f'(10) =
-8100 -0.01
(900)²
-
(d) Why is the rate of change so much smaller after 10 hours, compared to 1 hour?
Solution: After 10 hours one has probably forgotten most of the new facts, so they are
forgetting them at a much slower rate.
Transcribed Image Text:2. Some psychologists have said that the number of new facts a person can remember after hours is given by (a) How many facts are remembered after one hour? 90 Solution: f(1) = 99-90 = 10. f' (t) (b) What is the rate at which the number of facts remembered is changing after 1 hour? Solution: Let's compute the derivative of f: = f(t) = = 90t 99t - 90 = (99t-90) (90t)' - (90t) (99t-90)' (99t-90)² (99t90) (90) - (90t) (99) (99t-90)² 8910t8100 - 8910t (99t – 90)² -8100 (99t – 90)² So we get f'(1) = -8100 81 = -100. (c) What is the rate it's changing after 10 hours? Solution:Using what we did in part b, f'(10) = -8100 -0.01 (900)² - (d) Why is the rate of change so much smaller after 10 hours, compared to 1 hour? Solution: After 10 hours one has probably forgotten most of the new facts, so they are forgetting them at a much slower rate.
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