By what percentage will the transmission range of a T.V. tower be affected when the height of the tower is increased by 21% ?

To double the covering range of a TV transimitter tower, its height should be made

To double the covering range of a TV transimitter tower, its height should be made

What will be the percentage increase in the time period of a simple pendulum when its length is increased by 21% ?

The fundamental frequency of a sonometer wire increases by 5Hz, if its tension is increased by 21% .How will the frequency be affected if the length is increased by 10% /