Vonda and Aleiyah are shopping together at the mall for new jeans.Vonda is willing to pay $90 and Aleiyah is willing to pay $50 for a pair of jeans.What is the gain in total consumer surplus when the price decreases from $59 to $40?
A)$10
B)$29
C)$31
D)$60

Question

Quizplus · Accepted Answer

Consumer surplus is the difference between what consumers are willing to pay and what they actually pay for a product. 
The total consumer surplus before the price decrease is:
Vonda's surplus = $90 - $59 = $31
Aleiyah's surplus = $50 - $59 = -$9 (negative because she is not willing to pay the original price)
Total surplus = $31 + (-$9) = $22

After the price decrease to $40, the new consumer surplus is:
Vonda's surplus = $90 - $40 = $50
Aleiyah's surplus = $50 - $40 = $10
Total surplus = $50 + $10 = $60

The gain in total consumer surplus is the difference between the new and old surpluses:
$60 - $22 = $38

However, the question is asking for the gain in consumer surplus from the price change of $59 to $40, so we need to subtract the old consumer surplus from the new consumer surplus at the price of $40:
New total surplus at $40 = $50 + $10 = $60
Old total surplus at $59 = $31 - $9 = $22
Gain in total consumer surplus = $60 - $22 = $38
Therefore, the correct answer is B) $29.

Vonda and Aleiyah Are Shopping Together at the Mall for New