Answer: The average variable cost of producing a backpack is $15.
The formula for calculating the variable cost per unit using the high/low method is:
![Average Variable Cost = (y_(2) - y_(1))/(x_(2) - x_(1))](https://img.qammunity.org/2019/formulas/business/college/qn543z5b8oxrjitplfumgdye7s95zn2g1v.png)
where
y₂ : cost at highest level of activity
y₁ : cost at lowest level of activity
x₂ : number of units produced at highest level of activity
x₁ : number of units produced at lowest level of activity
Substituting the values from the question in the formula we get,
![Average Variable Cost = (110000 - 87500)/(4000 - 2500)](https://img.qammunity.org/2019/formulas/business/college/xsf38cfuoz219ta348zpk1oi8pbzet8cp0.png)
![Average Variable Cost = (22500)/(1500)](https://img.qammunity.org/2019/formulas/business/college/7vtut8gduz3dbaxuvztp0asfegf3k2j3pu.png)
![Average Variable Cost = 15](https://img.qammunity.org/2019/formulas/business/college/fdi86b562ukhwzyhidht2aqbwp7dv6umnk.png)