The manometer shown in Fig. P$2\mathrm{.}6\mathrm{.}6$R is used to measure the water pressure in the pipe.

Determine the pressure difference, $p_B-p_A$ if point B is $4$ ft higher than point A and $h=10\mathrm{.}3$

in$.$

$7\mathrm{.}5$ psi

$15$ psi

$3\mathrm{.}5$

$2\mathrm{.}9$ psi

$10\mathrm{.}5$ psi

$110$ psi