3. During a promotional campaign, a cell phone dealer allows purchasers of new cell phones to return them within 30 days if they are dissatised with their purchases for any reason. The cost to the dealer of such a refund is $100. The dealer estimates that 10% of all purchasers will return the cell phones and receive refunds. Suppose that 20 cell phones are purchased. What is the probability that more than 3 cell phones will be returned? Answer to 2 decimal places. 4. During a promotional campaign, a cell phone dealer allows purchasers of new cell phones to return them within 30 days if they are dissatised with their purchases for any reason. The cost to the dealer of such a refund is $100. The dealer estimates that 15% of all purchasers will return the cell phones and receive refunds. Suppose that 20 cell phones are purchased. The expected number of computers that will be returned Is