Question

Suppose that the number of pairs of clothes in a year by Americans is normally distributed and the mean number of clothes is 20 a year. Suppose that a researcher takes 1,990,000 samples of Americans, and each sample consists of 5 Americans. She asks each American how many pairs of clothes they buy in a year. She then calculates a mean for each of the 1,990,000 samples. If she added up the mean for each sample, and divided by 1,990,000, what would she get? Explain why. 5 point

. A widely used measure of infant development is the Psychomotor Development Index (PDI). Since the PDI has been used so frequently, we have a pretty good idea of the population mean and population standard deviation for scores on the PDI. The population mean is 100, and the population standard deviation is 15. Given this, what is the probability that:

a) In a sample of 100 infants, the sample mean PDI score is 101 or greater.

b) In a sample of 100 infants, the sample mean PDI score is 98 or less.

c) In a sample of 36 infants, the sample mean PDI score is 98 or less.

Answer 1