PristinDay Company produces handheld calculators. The company controller wanted to calculate the fixed and variable costs associated with the maintenance cost incurred by the factory. Data for the past four months were collected as follows:

Maintenance Machine Month

cost hours

June$5,000 350

July3,000 320

August4,000 315

September3,300 220

Coefficients shown by a regression program are as follows:

Intercept1,000

X Variable 18.5

Using the results of regression, calculate the variable rate of maintenance cost.

a.$8.50 per machine hour

b.$10.24 per machine hour

c.$12.00 per machine hour

d.$6.65 per machine hour