At what distance should an object be placed from a convex lens of focal langth `15 cm` to obtain an image three times the size of the object ?

At what distance should be placed from a convex lens of focal length 15 cm to obtain an image three times the size of the object?

A what distance must an object be placed from convex lens of power 4D to obtain a real image three times the size of the object ?

Calculate the distance at which an object should be placed in front of a convex lens of ocal length 10 cm,so as to obtain an image twice the size of the object?

Calculate two possible distances of an object from a convex lens of focal length 20 cm so as to obtain an image of double the size of the object.

Calculate the distance at which an object should be placed in front of a convex lens of focal length 10 cm to obtain a virtual image of double its size.

An object is placed at 15 cm from a convex lens of focal length 25 cm. State the nature and size of the image relative to that of the object.