A publishing company has just published a new college textbo

A publishing company has just published a new college textbook. Before the company decides the price at which to sell this textbook, it wants to know the average price of all such textbooks in the market. The research department samples 36 textbooks and finds the mean price is $70.50. It is known that the standard deviation is $4.50 and distribution is normal. Construct an 80% confidence about the true mean of all such textbooks.

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