The mean age of 25 teachers in a school is 40 years
A teacher retires at the age of 60 years and a new teacher is appointed in his place
If the mean age of the teachers in this school now is 39 years, then the age of the newly appointed teacher is
n=25, mean is 40mean=∑xn⇒∑x=25×40=1000New sum =1000−60+x=940+xNew average is 39940+x25=39975=940+xx=35