A study of $86$ savings and loan associations in six northwestern states yielded the following cost function.

where $C=$ average operating expense ratio, expressed as a percentage and defined as total operating expense $($$ million$)$ divided by total assets $($$

million$)$ times $100$ percent.

$Q=$ output; measured by total assets $($$ million$)$

$x_1=$ ratio of the number of branches to total assets $($ $ million$)$

Note: The number in parentheses below each coefficient is its respective t$-$statistic.

Holding constant the effects of bank branching $(x_1),$ what is the level of total assets that minimizes the average operating expense ratio?

$$1,557\mathrm{.}42$ million

$$688\mathrm{.}93$ million

$$1,377\mathrm{.}87$ million

$$461\mathrm{.}81$ million

What is the average operating expense ratio for a savings and loan association with the level of total assets determined in the previous part and $1$

branch?

$0\mathrm{.}90\%$

$1\mathrm{.}18\%$

$4\mathrm{.}94\%$

$3\mathrm{.}44\%$

What is the ratio with $10$ branches instead?