The formula of minimum speed at which the car will skid, in terms of the radius of the road, coefficient of friction between tyre's and road, acceleration of the car, and acceleration due to gravity, 
$v={\left[\left({\mu }^2{g}^2-a^2\right)R^2\right]}^{\frac{1}{4}}$, it means, 
$\Rightarrow v={\left[\left(0.5^2{10}^2-3^2\right){16}^2\right]}^{\frac{1}{4}}=8 \mathrm{m} {\mathrm{s}}^{-1}$