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

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a) What was the average score when they initially took the test, t = 0?
S(t) =28 - 20 log (t+1), t>(greater than) 0

You say your equation is not valid for t=0. Why not?

I would assume S(0) = 28 - 20log1 = 28

Note that negative scores are possible for n>26, which seems unlikely

To find the average score when the students initially took the test (t = 0), we can substitute t = 0 into the equation S(t) = 28 - 20 log (t+1).

Let's perform the substitution:

S(0) = 28 - 20 log (0+1)
S(0) = 28 - 20 log (1)
S(0) = 28 - 20 * 0 (since log(1) equals 0)
S(0) = 28 - 0
S(0) = 28

Therefore, the average score when the students initially took the test (t = 0) is 28%.