I'm having trouble with this word problem:
Priority Mail is the U.S. Postal Service's alternative to commercial express mail companies such as FedEx. An article in The Wall Street Journal presented some interesting conclusions comparing Priority Mail shipments with the much less expensive first-class shipments. When comparing shipments intended for delivery in three days, first-class deliveries failed to deliver on time 19% of the time, while Priority Mail failed 33% of the time. Note that at the time of the article, first-class deliveries started as low as $0.34 and Priority Mail started at $3.50.
If 10 items are to be shipped first-class to 10 different destinations claimed to be in a three-day delivery location, what is the probability that
a. 0 items will take more than three days?
b. exactly 1 will take more than three days?
c. 2 or more will take more than three days?
d. What are the mean and the standard deviation of the probability distribution?
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1 answer