While the mail-order DVD rental market has slowed with the advent of streaming, mail-order is still the only way to find rare movies. Raredvds.biz is considering moving into the rental business after considerable success selling DVDs. To gauge their customer service, they are considering the case of the 1980 film The Monster Clubfeaturing Vincent Price. Raredvds.biz expects to have one copy of the DVD. Based on data collected from customers, Raredvds.biz believes that the average time between orders for the film will be about 10 days with a coefficient of variation of one. Using customer data, the company also believes that including shipping time, both ways, the DVD will on average spend seven days in service, with a coefficient of variation of one. How long does a customer wait on average before being shipped the DVD?

a. 23.3

b. 7

c. 0

d. 16.3