Answer: 
The Marginal Cost of the new baker is $1.60. 
Step-by-step explanation: 
Consider the provided information. 
Baker would earn $20 per hour, that means 
Baker Wage = $20 per hour 
 Baker will work for 8 hours 
 So the total money baker will earn is: 
Total cost = 8 × 20 = $160 
 Baker produce 100 pastries. 
That means the quantity is 100. 
 
Where ΔTC is the total cost and ΔQ is the quantity. 
 Substitute the respective values in the above formula. 
 
Hence, the Marginal Cost of the new baker is $1.60.