Finding height of image for a concave mirror

[chester89]

Ok, there's something I just don't understand. I know that to find the height of an image (hi), you need to use the magnification equation m = -di/do = hi/ho. And for this question, the focal length (f), distance of object (do), and distance of image (di) are given. Now, if I want to find the height of the image (hi), I would need the height of the object (ho) to finish the equation, but I don't, so now I'm stumpted on what to do with this question.

I know 'hi = -diho/do' is the equation but if I don't have ho, than how can I find hi.

Any help would be greatly appreciated.

 

[mezarashi]

Edited, misinterpretation.

I don't believe you can find the height of the image without the height of the object. The focal length and a given object distance will determind the image distance. No other focused distance is possible. We cannot arbitrarily choose some image distance.