Question 131974: You are entered in a driving contest and you are expected to maintain an average speed of 60 mph for two miles. Unfortunately, your car develops a miss and you can only maintain a speed of 30 mph for the first mile. How fast do you have to drive the second mile in order to meet the overall average speed requirement? (I thought is was 90 mph, but that is incorrect.) Answer by ptaylor(2052) (Show Source):
If you expect to maintain an average speed of 60 mph for two miles, that means that you need to drive the two miles in 2 minutes.
At 30 mph for the first mile means that you have already used up your two minutes, so it's impossible to average 60 mph for the two miles.
Ans: Can't be done.
Hope this helps---ptaylor