Joan loves sushi.Her first piece of sushi normally gives her a marginal benefit of $5.Each additional piece yields a marginal benefit that declines by $0.25 per piece.If her favorite sushi bar charges $2.75 per piece of sushi,how many pieces should she eat?

Question

Quizplus · Accepted Answer

Joan should keep eating sushi until the marginal benefit she gets from eating one more piece is equal to the price she pays for it.

Let x be the number of sushi pieces that Joan eats. 
Marginal benefit of the first piece = $5 
Marginal benefit of the second piece = $4.75 
Marginal benefit of the third piece = $4.50 
... 
Marginal benefit of the xth piece = $5 - ($0.25 * (x-1))

She should keep eating sushi until the marginal benefit of the next piece is equal to $2.75.

$5 - ($0.25 * (x-1)) = $2.75

Solving for x: 
($0.25 * (x-1)) = $2.25 
x-1 = 9 
x = 10

So, Joan should eat 10 pieces of sushi.

Joan Loves Sushi