The average height of a class of 14 boys is 5.3 feet. A new boy admitted to the class, the new average of height now becomes 5.25. What is the height of the new boy ?
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 rectangle is 16 cm long and 10 cm wide. If the length is reduced by k cm and its width is increased also by k cm so as to make it a square then its area changes by