If a pipe can fill a tank in 2 hours and another pipe can fill the same tank in 40 minutes. How much time in minutes is needed to fill the tank if both the pipes are working together ?
A car that gets 15 miles per gallon of gasoline can travel 250 miles on a full tank. If the same car got 20 miles per gallon, how many miles could it travel on a full tank ?
A word processing operator typed 44 words per minute. After practice, the operator's speed increased to 55 words per minutes. By what percent did the operator's speed increase ? (25%)