An online retailer sells clothing to customers on its web-site. The retailer has two types of customers: account holders (who has an online account) and guests (who has not an online account). A survey of 1000 customers of the company reports that 395 of them have used a discount coupon at least once, 600 of them are account holder customers, 253 of them are guest customers who have never used a discount coupon before. Answer the following questions according to the information given above and submit your answers using the drop-down menus given below. a) What is the probability that a customer has used a discount coupon at least once? b) What is the probability that a guest customer has used a discount coupon at least once? c) What is the probability that a customer has used a discount coupon at least once if they are known to be a guest customer?