The effectiveness of a television commercial depends on how many times a viewer watches it. After some experiments an advertising agency found that if the effectiveness E is measured on a scale of 0 to 10, then

E(n) =

2

3

n −

1

69

n^{2}

where n is the number of times a viewer watches a given commercial. For a commercial to have maximum effectiveness, how many times should a viewer watch it?

Thank you for the opportunity to help you with your question! the solution is as such:

for maximum effectiveness E(n)=10 by the scale of 0 to 10

so we have 10=2/3n-1/69n^2 rearrange and set to 0

so n= 23

so a viewer must watch it 23 times.

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