A marketing researcher wants to estimate the mean amount spent ($) on a certain retail website by members of the website's premium program. A random sample of 100 members of the website's premium program who recently made a purchase on the website yielded a mean of $1200 and a standard deviation of $250.

a. Construct a 90% confidence interval estimate for the mean spending for all shoppers who are members of the website's premium program.

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(Round to two decimal places as needed.)