How was the cost estimate for apparatus replacement determined?

If we ordered today a new fire engine, like the one most recently purchased, that engine would cost $650,000. Recent history instructs us that the cost of fire trucks is rising much faster than the number of homes and businesses in our district is increasing. Thus we are have used a cost of $750,000 per engine as the average cost over the next 25 years. We may later find that this estimate is low. If it proves to be, then later apparatus purchases may have to be delayed.

Thus an increase of 0.27 mills would have yielded for 2010 a total mill rate of 1.87 vs. 1.60.