The distance between the driver and driven pulley is $15$ inches.

$*$Determine the length of the belt if the diameter of the driver and driven pulleys are $3$ inches and $6$ inches respectively.

$*$What is the torque output in the driven pulley if a power of $3\mathrm{.}5$ Hp is applied in the driver pulley rotating at $2500$ RPM if the transmission system is $90\%$ effecient?