if sound travels 6770 feet in 6.4 seconds. how far will it travel in one minute
6770 *60/6.4 = 63,470 feet/minute
By the way those of us who work at sea figure about 5 seconds per nautical mile.
Some lighthouses flash at the same time as they sound a horn. If you hear the horn five seconds after you see the flash, you are a mile away from the lighthouse.