Answer:
image height is 2.9 cm
Step-by-step explanation:
We have given the size of the object O = 8 cm
Distance of the object from the lens = 15 cm
Focal length of the lens = 4 cm
Now for lens we know that

So

v = 5.454 cm
Now magnification

Now magnification is the ratio of image height and object height
So
, where I is the height of image and O is the height of object
So

I =2.9 cm