Tuesday, May 18, 2010

May 2010 Newsletter Brain Teaser Solution

Tom can beat Dick by one-tenth of a mile in a five-mile race. Dick can beat Harry by one-fifth of a mile in a five-mile race. By how much can Tom beat Harry in a five-mile race?

Tom runs 5 miles in the time it takes Dick to run 4.9 miles.  This is a rate of 98% or .98.
Dick runs 5 miles in the time it takes Harry to run 4.8 miles.  This is a rate of 96% or .96.

So the rate of Harry to Dick is (0.98)(0.96)5 so Harry was 4.704 miles along when Tom finished.
So Tom beat Harry by 0.296 miles.

1 comment:

Charlie said...

I got the same answer calculating the velocity of each runner V=D/T