If the momentum of a body is increased by 50%, its kinetic energy will increase by

Let initial momentum be p. increase by 50% implies that new momentum is $p+\frac{p}{2}$  i.e. $\frac{3}{2}p$ 

Since,

$K=\frac{p^2}{2m}$

$\Rightarrow K\propto p^2$

So, new kinetic energy becomes $\frac{9K}{4}$ .

Percentage increase $=\left(\frac{9}{4}-1\right)\times 100=125\%$