Calculating Diopters for Bifocals: What Power Should They Have?

[DrMcDreamy]

Homework Statement

This is a 2 part problem:

4- A person is to be fitted with bifocals. She can see clearly when the object is between 49 cm and 1.5 m from the eye. The upper portions of the bifocals should be designed to enable her to see distant objects clearly. What power should they have? Answer in units of diopters.

5- The lower portions of the bifocals should en- able her to see objects comfortably at 25 cm. What power should they have? Answer in units of diopters.

Homework Equations

P=$$\frac{1}{f}$$

The Attempt at a Solution

4- P = $$\frac{1}{0.49 m}$$ = 2.04 x 100 = 204 D
or it might be P = $$\frac{1}{1.5 m}$$ = 0.666 x 100 = 66.6 D

5- P = $$\frac{1}{0.25 m}$$ = 4 x 100 = 400 D

I know I am doing something wrong can you help me?! TIA

 

[DrMcDreamy]

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[DrMcDreamy]

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