<p>And here’s another obnoxoius viariation on the theme:</p>
<p>You ride your bike at 30 km/hr from your house to the base of a big hill. Then you ride at 20 km/hr going up the hill. Then you zip back down the hill at 60 km/hr. And then you go back home at 30 km/hr again. </p>
<p>Your average speed for the trip is…?</p>
<p>a) 30 km/hr
b) 35 km/hr
c) 110/3 km/hr
d) 40 km/hr
e) Can’t be determined without more information</p>