Question

Christmas A recent survey revealed that American’s Christmas spending averaged $830. Use this as the population mean American’s Christmas spending. Suppose American’s Christmas spending is normally distributed with a standard deviation of $220. Random samples of size 100 are selected from the population of American consumers.

a.) What is the probability that the sample mean spending is less than $900?

ANSWER: 

b.) What is the probability that the sample mean spending is at least $800?

ANSWER:

c.) What is the probability that the sample mean spending is between $820 and $840?

ANSWER: 

d.) The middle 50% of the sample mean spending will be bounded by what two values?

ANSWER:

e.) You work for Apple in the iPhone division. How might this information be useful? What information was omitted from the summary of this scenario that would be particularly useful insight for your division? (There is something missing directly from the word problem. After you identify that, feel free to think beyond the scope of the information provided.)