Swifty Company sells automatic can openers under a $75-$day warranty for defective merchandise. Based on past experience, Swifty estimates that $4\%$ of the units sold will become defective during the warranty period. Management estimates that the averas replacing or repairing a defective unit is $$20.$ The units sold and units defective that occurred during the last $2$ months of $2022$ are as follows.

$\backslash$table$[[$Month$,$Units Sold,Units Defective Prior to December $31],[$November$,31,600,632],[$December$,33,600,420]]$