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 ?
The average height of a class of 14 days is 5.3 feet. After new boy is admitted to the class ,the new average height now becomes 5.25. What is the height of the new boy?
A rectangular lot 50 feet by 100 feet is surrounded on all sides by a concrete walk 5 feet wide. Find the number of square feet in the surface of the walk.
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%)