For this question, I drew the proper figure, found out the height of image using lens formula in rough sheet and marked the answers in the answer sheet properly. So will I get full credits? As only ray diagram is asked....I did the calculations in rough sheet...meritnation
Q. An object of height 2.5 cm is placed at a distance of 15 cm from the optical centre 'O' of a convex lens of focal length 10 cm. Draw a ray diagram to find the position and size of the image formed. Mark optical centre 'O', principal focus F and height of the image on the diagram.

Dear Student ,
Image result for image formation when an object is placed in between the focus and radius of curvature of a convex lens

In the ray diagram object size=AB=4 cm,  the focal length=CF=20cm, object distance =CB=u=30 cm, so the image at distance v is formed at:            1f=1v-1uor           120=1v-1-30or              1v=120-130=130or                v=60cmWe know that   IO=vusoIO=6030=21
This is the full answer given above .
Hence if you write the full answer then you will get full marks .But if only diagram is drawn then you could get half of the total marks .

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This question was of 3 marks; 2 marks for the diagram and answering the nature and position of image and 1 mark for answering the ratio.
And exact answer is, 
And, 2:1 is the ratio.
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Yes. I did that much
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Not lens formula, I didn’t show. I did it in rough
will my mark be cut
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Yes surely your marks will be cut.
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