Which Team is the Fastest?

A QUESTION OF TIME..?

As part of our IPC topic on the Olympics, we decided to run a relay race around part of our school grounds to see which team was fastest.  We have four house teams, Emerald, Ruby, Sapphire and Topaz.  Each student ran the 360m course and 'tagged' the next member of their team.  Individual times were recorded by hand using digital stopwatches.  Two teams ran at a time so that the others could do the timing.

However, despite our organisation, one person's time was not recorded.  In addition, the teams that didn't have 5 members had to have someone run twice which resulted in a much slower time.  This then led to thinking about what we should do to put this right.  Should we run again another day, or could we use mathematics to come up with a solution?  

So our problem is this, how do we make it fair for the teams with 4 members to compete with a team of 5?