(a) In a certain culture of bacteria the rate of increase is proportional to the number present. (i) If it is found that the number doubles in 8 hours, how many may be expected at the end of 24 hours? (ii) If there are 108 at the end of 7 hours and 4 x 108 at the end of 9 hours, how many were there in the beginning?
(a) In a certain culture of bacteria the rate of increase is proportional to the number present. (i) If it is found that the number doubles in 8 hours, how many may be expected at the end of 24 hours? (ii) If there are 108 at the end of 7 hours and 4 x 108 at the end of 9 hours, how many were there in the beginning?
Chapter6: Exponential And Logarithmic Functions
Section6.1: Exponential Functions
Problem 60SE: The formula for the amount A in an investmentaccount with a nominal interest rate r at any timet is...
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![(a) In a certain culture of bacteria the rate of increase is proportional to the number
present.
(i) If it is found that the number doubles in 8 hours, how many may be expected
at the end of 24 hours?
(ii) If there are 108 at the end of 7 hours and 4 x 108 at the end of 9 hours, how
many were there in the beginning?
(b) According to Newton's law of cooling, the rate at which a substance cools in
moving air is proportional to the difference between the temperature of the substance
and that of the air. If the temperature of the air is 32° and the substance cools from
100° to 70° in 15 minutes, find when the temperature will be 42°.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F1d61e5f9-3465-4e8b-8fb1-c92dedd07144%2F3bae308e-f418-4afc-b8eb-9f4f76bb4d64%2Fzcdu9ns_processed.jpeg&w=3840&q=75)
Transcribed Image Text:(a) In a certain culture of bacteria the rate of increase is proportional to the number
present.
(i) If it is found that the number doubles in 8 hours, how many may be expected
at the end of 24 hours?
(ii) If there are 108 at the end of 7 hours and 4 x 108 at the end of 9 hours, how
many were there in the beginning?
(b) According to Newton's law of cooling, the rate at which a substance cools in
moving air is proportional to the difference between the temperature of the substance
and that of the air. If the temperature of the air is 32° and the substance cools from
100° to 70° in 15 minutes, find when the temperature will be 42°.
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