The following Excel scatterplot with the fitted quadratic regression equation illustrates the observed relationship between productivity and the number of hired workers. 
Assuming that the number of hired workers must be integer,how many workers should be hired to achieve the highest productivity?
Definitions:
Expected Value
A statistic that measures the mean, or average, outcome of a set of probabilities or a random variable.
English Auction
A method of auctioning in which the price ascends with successive bids and remains with the highest bidder who then wins the auctioned item.
Reservation Price
The maximum price a consumer is willing to pay for a good or service, beyond which they would prefer not to make a purchase.
Expected Revenue
The amount of money a business anticipates receiving from the sale of goods or services over a certain period, based on predicted sales volume and price.
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