(Solved): Most dermatologists recommend using sunscreens that have a Sun Protection Factor (SPF) of at least 3 ...

Most dermatologists recommend using sunscreens that have a Sun Protection Factor (SPF) of at least 30. A professor wanted to find out whether the SPF of sunscreens used by students at the professor's school exceeds this value on average. To collect data, the professor surveyed students in the introductory statistics course and found that in a sample of 48 students, the mean SPF was 35.29, and the standard deviation of SPF was 17.19. Using the 2SD method, the approximate

confidence interval for the population mean is.

Expressed in terms of its endpoints, the interval can also be written as

,

).

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