# Math Help - writing equations

1. ## writing equations

One seventh of the people with a certain disease show visible symptoms. One in three-hundred people without the disease show false symptoms. One person in one-hundred of the general population shows symptoms of the disease. Let r be the fraction of the general population that has the disease. Write an equation reflecting the above information.

2. The fraction of the general population that does not have the disease is 1-r, and the fraction of the general population showing symptoms is just the sum of the fraction showing real symptoms and the fraction showing false symptoms:

$\frac{1}{7}r+\frac{1}{300}(1-r)=\frac{1}{100}$

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3. nice posting