A train covered half a trip at 30 miles per hour and the other half at 60 miles per hour. If the whole trip was 20 miles, how much time did the train take?

The train took 30 minutes.

Each half of the 20 mile trip is 10 miles.

Time for first half = 10 / 30 = 1/3 hour.

Time for second half = 10 / 60 = 1/6 hour.

Total = 1/3 + 1/6 = 1/2 hour = 30 minutes.

So the trip took 30 minutes.