Given, image size = 3U
object size = U
focal length = 10cm
lens to object distance = focal length × object sizeimage size\frac{\text{focal}\:\text{length}\:\times\:\text{object}\:\text{size}}{\text{image}\:\text{size}}imagesizefocallength×objectsize
= 10 × u3u=3.33\frac{10\:\times\:u}{3u} = 3.333u10×u=3.33
distance between image and object = 10 + 3.33 = 13.33cm
