Answer:
1a. $500
1b. $250
2. The market for sunscreen is efficient because total surplus is maximum.
<em>Diagram in question attached</em>
Explanation:
1a. Consumer surplus is the difference between the maximum price that consumers are willing to pay and the price actually paid. This is the triangular area above the market equilibrium. In the market for sunscreen, consumers are willing to pay $20 for sunscreen but are actually only paying $10 (equilibrium price).
The formula for consumer surplus = 1/2 x (Qd at equilibrium) x (price willing to pay - price at equilibrium)
<em>Note that consumer surplus is a triangle and the area of it is being found, hence the 1/2 :)</em>
Consumer surplus = 1/2 x 100 x ($20 - $10)
1/2 x 100 x $10 = $500
1b. Producer surplus is the difference between the price producers receive and the minimum price they are willing to accept. This is the triangular area below the market equilibrium. In the market for sunscreen, suppliers are willing to produce at $5 but are actually receiving $10 (equilibrium price).
The formula for producer surplus = 1/2 x (Qs at equilibrium) x (price at equilibrium - price willing to receive)
Producer surplus = 1/2 x 100 x ($10 - $5)
1/2 x 100 x $5 = $250
2. The market for sunscreen is efficient because total surplus is maximum. Total surplus is maximized when the market is producing at the equilibrium price as in the current sunscreen market. At any other price, consumer or producer surplus would be reduced and a dead weight loss would be incurred.