SOLUTION: Students in an english class took a final exam. They took quivalent forms of the exam at monthly intervals thereafter. The average score S(t), in percent, after t months was found

Question 753693: Students in an english class took a final exam. They took quivalent 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 > or = to 0.
1.What is the average score when they initially took the test, t=0?
2.What is the average score after 14 months?
3.After what time t was the average score of 40%?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Students in an english class took a final exam. They took quivalent 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 > or = to 0.
1.What is the average score when they initially took the test, t=0?
S(0) = 68-20*log(1) = 68-20*0 = 68
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2.What is the average score after 14 months?
S(14) = 68-20*log(15) = 68-23.52 = 44.48
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3.After what time t was the average score of 40%?
40 = 68-20*log(t+1)
20*log(t+1) = 68-40
----
20*log(t+1) = 28
log(t+1) = 1.4
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t+1 = 10^1.4 = 25.12
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t = 24.12
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Cheers,
Stan H.
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