Answer:
b) 100 cars per day.
Explanation:
With the information above, we can conclude that each worker washes 20 cars per day, and earns a wage of $60 per day.
So the total labor costs per day is $60 wage per worker X 4 workers = $240
The total sales revenue per day is: 80 cars washed per day X $5 per wash = $400.
So, we can see that with four workers, the firm has a good profit of = $400 - $240 = $160.
If the firm hired a fifth worker, labor costs would increase to $320 ($240 + $60), the amount of cars washed would increase to 100, and the sales revenue would increase to $500 (100 x $5).
So, profits would increase to $180 ($500 - $320) if the firm hired a fifth worker.
However, productivity should still be stable, so a worker who washed less than 20 cars per day should not be hired, this is why the A option is wrong.
