Determine the multifactor productivity measure for the current year for a factory which, $in$ a ten$-$hour workday produced a usable output $of3950$ units using four workers and $800$ pounds $of$ materials. The workers made $$\frac{25}{h}$our, the materials cost $$1\mathrm{.}50$ per pound, and overhead was $1\mathrm{.}75$ times the labor cost.