Stage: 4 Challenge Level: 
I drove from Cambridge to Cardiff at an average speed of 50 mph, it was heavy traffic, but I managed to drive back at an average speed of 70 mph. Why wasn't my average speed for the round trip 60mph ?
What average speed for the return journey would make the round trip average 60 mph ?
chemistry. Rotations. Differentiation. Interactivities. Discussion. Rates of change. Vector geometry. Complex numbers. Speed. Learning through exploration.
Published May 2008.
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