Solve clearly I will give upvote

A call center has 12 representatives ready to assist customers from 8:00 a.m. until 5:00p.m. Calls come into the call center at a rate of almost 35 calls per hour. The time customers must wait on hold before getting assistance are normally distributed with a mean of 28.0 minutes with a standard deviation of 8.1 minutes. What time represents the 30th percentile? (i.e. wait time that is longer than 30% of all other wait times )