Posted 06 August 2009 - 05:13 PM
Yes, you have misunderstood.
The question is looking at the order all 6 animals finish in. So you could have
That's all the ways with a Horse first. By symmetry, there will also be 10 ways with a Zebra first.
So, there are 20 ways the 6 animals can finish the race, if we are not interested in individuals.