Math CentralQuandaries & Queries


hi my problem is:

a man that is 6 feet tall in real life and only .5 inches in a photograph. what is the scale factor and scale of the photograph?


a girl in the same photograph is 4.8 feet tall. How tall is she in the picture?


The question cannot be answered without further information: the scale factor depends on the distance of the object from the camera. At that distance the scale factor is 72 to .5 or 144 to 1 (which is usually written 144:1). The image of a girl who is 4.8 feet tall (= 4.8 X 12 inches) and standing at the same distance as the man from the camera would satisfy the equation,
1/144 = x/ (4.8*12).

An easier way to approach this particular problem is to observe that 4.8/6 = 4/5: the girl is 4/5 as tall as the man, so her image would be 4/5 as large as the man's.


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