Centripetal acceleration is given as
[tex]a_c = \frac{v^2}{R}[/tex]
here we know that
v = speed of the car
R = radius of curvature of the car
now here we can see that the acceleration of car directly depends on the square of the speed
so here if speed of the car is tripled then centripetal acceleration will be increased by square times
so here centripetal acceleration is increased by 9 times if speed is tripled