Customers Arrive at the Local Grocery Store Every 30 Seconds

Customers arrive at the local grocery store every 30 seconds on average.Thirty percent of these customers spend an average of 15 minutes shopping and purchase 10 items or less.These lucky customers go to the express line where they enjoy an average checkout time of 5 minutes.Customers that don't meet the express line criterion average 40 minutes in the store and go to checkout line #2 where they spend an average of 10 minutes checking out.How many people are checking out at any given time?

A) Greater than 15
B) Greater than 10 but less than or equal to 15
C) Greater than 5 but less than or equal to 10
D) Less than or equal to 5