If the height of the transmitting tower is increased by $30 \%$,then the area covered by it increases by (in $\%$)

If the maximum and minimum amplitudes of a modulated wave are $25 \ V$ and $5 \ V$ respectively,then the modulation index is

If the frequencies of the carrier wave and message signal are $1 \text{ MHz}$ and $28 \text{ kHz}$ respectively,then the frequencies of the side bands are

For transmission of e.m. wave of audible frequency,these waves are superimposed with waves of

This question has Statement-$1$ and Statement-$2$. Of the four choices given after the statements, choose the one that best describes the two statements.
Statement-$1$: Sky wave signals are used for long-distance radio communication. These signals are, in general, less stable than ground wave signals.
Statement-$2$: The state of the ionosphere varies from hour to hour, day to day, and season to season.

$A$ $TV$ transmission tower of height $h$ covers a range of distance $d$. By how much will the range change if the height is increased to $3/2 h$?