If we consider that company

$($

in question

$3$

$)$

$$manufactures dishwashers in four stages and inspection occurs at each stage of the process. The average percentages of good quality units are as follows.

$1-87\%,2-91\%,3-94\%,4-93\%.$

a$.$Determine the weekly product yield of good$-$quality dishwashers. $($round to $2$ decimal places.$)$

b$.$ What would weekly product input have to be to acheive a final weekly product yield of $300$ dishwashers?