a random sample of 12-ounces milkshakes from 11 fast food restaurants had the following number of calories.

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476 580 504 473 375 700 510

591 472 399 450

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assume the population standard deviation is o=86

part 1) explain why it is necessary to check whether the population is approximately normal before constructing a confidence interval.

it is necessary to check whether the population is approximately normal because which of the following

a. the sample size is less than or equal to 30

b. the sample standard deviation is not known

c. the population mean is not known

d. the population standard deviation is not known