A graph titled Marginal Cost of Bikes has the bike number of the x-axis, from 1 to 7, and marginal cost on the y-axis, from 0 to 70 dollars in increments of 10. Bike 1 is 30 dollars, bike 2 is 18 dollars, bike 3 is 12 dollars, bike 4 is 20 dollars, bike 5 is 30 dollars, bike 6 is 50 dollars, and bike 7 is 60 dollars. This graph shows the marginal cost of producing each bike. Select the correct answer from the options available. Based on this graph, which bike has a marginal cost of $20? Bike 1 Bike 2 Bike 3 Bike 4

Marginal Cost of Bikes

A graph titled Marginal Cost of Bikes has the bike number of the x-axis, from 1 to 7, and marginal cost on the y-axis, from 0 to 70 dollars in increments of 10. Bike 1 is 30 dollars, bike 2 is 18 dollars, bike 3 is 12 dollars, bike 4 is 20 dollars, bike 5 is 30 dollars, bike 6 is 50 dollars, and bike 7 is 60 dollars.

This graph shows the marginal cost of producing each bike. Select the correct answer from the options available.

Based on this graph, which bike has a marginal cost of $20?

D: Bike 4

what is the original number? you forgot to add it.