Your sentence is not complete. Please proofread your questions before sharing them.
I think you meant:
"Buses on your route run every 11 minutes from 7 AM to 11 AM. YOU arrive at the bus stop at 8:18 AM how long will you HAVE TO wait for a bus?"
Let's try this:
First bus arrives at 7 a.m. The next one arrives at 7:11, the next at 7:22, the next at 7:33, the next at 7:44, the next at 7:55, the next at 8:06, the next at 8:17, and the next at 8:28. You'll have to wait 10 minutes for the 8:28 bus.