A hand driven tire pump has a piston with a $2\mathrm{.}50$ cm diameter and a maximum stroke of $30$ cm$.$

a$)$ How much work do you do in one stroke if the average gauge pressure is $2\mathrm{.}40$x$10^5$ N$/$m$^2?$

b$)$ What average force do you exert on the piston, neglecting friction and gravitational force $?$