A slab of a material of refractive index 2 shown in the figure, has a curved surface APB of radius of curvature 10cm and a plane surface CD. On the left oa APB is air and on the right of CD is water with refractive indices as given in the figure. An object O is placed at a distance of 15cm from the pole P as shown. The distance of the final image of O from P, as viewed from the left is