Students participating in a psychology experiment attended s

Students participating in a psychology experiment attended several lectures and were given an exam. Every month for the next year, the students were retested to see how much of the material they remembered. The average scores for the group are given by the model f(t) = 90 - 15log(t + 1), 0 lessthanorequalto t lessthanorequalto 12 where t is the time (in months). Algebraically answer the following: a) What was the average score on the original exam (t = 0)? b) What was the average score after 12 months? c) When will the average score decrease to 75?

Solution

Solution:

A)

at t = 0

f(t=0) = 90-15log(0+1)

=> f(0) = 90 -15(0)

=> f(0) = 90

B)

for t = 12

f(t = 12) = 90-15log(12+1)

=> f(12) = 73.2908

C)

here;

f(t) = 75 = 90-15log(t+1)

=> 15 log(t+1) = 15

=> log(t+1) = 1

=> t + 1 = 10

=> t = 9