Let the number of times she turns the pedal in one mile be x.
Given that her rear miles turns 875 times in one mile and the ratio of pedal turns to rear wheel turns is 4 to 7, then
[tex] \frac{4}{7} = \frac{x}{875} \\ \\ \Rightarrow 7x=4(875)=3,500 \\ \\ \Rightarrow x= \frac{3,500}{7} =\bold{500}[/tex]
Therefore, she turns the pedal 500 times in one mile.
