$($a$)$ The print in many books averages $3\mathrm{.}50$ mm in height. How high is the image of the print on the retina when the book is held $30\mathrm{.}0$ cm from the eye?

$($b$)$ Compare the size of the print to the sizes of rods and cones in the fovea and discuss the possible details observable in the letters. $($The eye$-$brain system can perform better because of interconnections and higher order image processing.$)$