2) 95% confidence interval estimate of the (true, unknown) mean sound intensity of all food processors of this type is C.I = ( 48.071, 52.529).
if the population standard deviation is unknown then we will use t-distribution and assume that population is normally distributed.
C.I = 50.3 + 2.306 × 0.96667
C.I = 50.3 + 2.2291
C.I = ( 48.071, 52.529)
The length of the confidence interval obtained here will be greater than the the length obtained in Exercise 1, because the t-critical value is always greater than z-critical value for the same confidence level.
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