UGC NET Paper 1 GA 2013 June Solved Paper

Perimeter of circle (p) $=2\mathit{\pi }\mathit{r}$
when radius (r) increased by 50%
$\mathit{r}\prime =\mathit{r}+\frac{\mathit{r}\times 50}{100}=\frac{3\mathit{r}}{2}$
New Perimeter (p') = 2πr’ = 3πr
Increase in perimeter p' – p = 3πr – 2πr = πr
Percentage increment = $\frac{\mathit{\pi }\mathit{r}}{2\mathit{\pi }\mathit{r}}\times 100=50\%$