The population of 8 villages is 900, 750, 1100, 1050, 835, 1250, 555, and 630. Find teh population of Ninth village if the average population of Nine villages is 900.
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?
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 ?