college algebra

3. Students in an English class took a final exam. They took equivalent forms of the exam at monthly intervals thereafter. The average score S(t), in percent, after t months was found to be given by
S(t) = 68 − 20 log (t + 1), t ¡Ý 0.
What was the average score when they initially took the test, t = 0?
Show your work in this space:
What was the average score after 4 months? after 24 months?

After what time t was the average score 50%?Round your answe

1. when t = 0
S(0) = 68 - 20log(1) = 68

when t= 4
S(4) = 68 - 20log(5) = 54.02... or 54

etc.

for score to be 50
50 = 68 - 20log(t+1)
log(t+1) = 18/20 = .9
t+1 = 10^.9
t = 10^.9 - 1 months
= 6.943 or appr. 7 months

posted by Reiny

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