Historical data has shown that the average annual revenue per customer was $1010, and 20% of the customers had a negative experience with the store's overall service. The new store manager is determined to increase the average annual revenue per customer and reduce the proportion of customers with negative experience to less than half of the historical value. She simplified various customer service processes and improved the employee training program. At the end of the year, she takes a random sample of 250 customers and finds that:

Average revenue per customer is $1021; Standard deviation $92.

18 customers said they have negative experience with the store's overall service. Does this result show that she has achieved her goal?

Please solve through excel