Rays from Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object?

We know that in case of a concave mirror, when the object is placed at infinity, then the light rays after reflection gets converged at focus of the concave mirror. Sun is at the infinity point, So focal length of the mirror will be 15 cm. The object should be placed between at 2f to obtain the same size of image as that of the object.

So, object distance = 2f = 2 x 15 = 30 cm