Tom's Hardware has two suppliers of lightbulbs, Factory A and Factory B. Factory A produces 20% of the lightbulbs supplied to Tom's Hardware and Factory B produces 80%. 10% of the bulbs produced by Factory A are defective while 20% of the bulbs produced by Factory B are defective. A customer who purchased a light bulb from Tom's Hardware is selected at random.

a. (5 points) What is the probability the light bulb purchased is defective?

b. (5 points) If 100 customers are selected at random, what is the probability exactly 10 purchased defective light bulbs?

c. (5 points) How many of the 100 should I expect to have purchased defective light bulbs?

d. (5 points) A light bulb purchased at Tom's Hardware is defective. What is the probability the light bulb was manufactured by Factory B?

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