Use GUESS problem$-$solving to complete the following questions.

$10.$

A speaker attached to a movable cart is emitting a sound with a frequency of$698\mathrm{.}5$ Hz$.$ If the speed of sound in the air is $348$ m$/$s$,$ how fast should the cartmove $($and in what direction$)$ for an observer to hear the frequencies $659\mathrm{.}3$ Hzand $740\mathrm{.}0$ Hz$?$

$(7$ marks$)$

$11.$

An open air column with a length of $1\mathrm{.}00$ m is placed in a room with a speed ofsound of $332$ m$/$s$.$ What are the first and second resonant frequencies of theopen air column?

$(5$ marks$)$