Two circles of same radius intersect each other at P and Q. If the length of the common chord is 30 cm and distance between the centres of the two circlesis 40 cm, then what is the radius (in cm) of the circles?
The average age of fifteen persons is 32 years. If two more persons are added, then the average is increased by 3 years. The new persons have age difference of 7 years. The age (in years) of the younger among the new persons is: