During a road trip, Richard drove his car at 80mph for 1 hour, and then at 60mph for 1 1/2 hours. What was the average speed for the entire journey?
Avg Speed = Total distance / Total time
So we have
[ 80 * 1 + 60 * 1.5 ] / [ 1 + 1.5 ] =
[ 80 + 90 ] / [ 2.5 ] =
[ 170 ] / [ 2.5 ] =
68 mph
+4623 
