In 2013, selected automobiles had an average cost of $15,500. The average cost of those same automobiles is now $17,205. What was the rate of increase for these automobiles between the two time periods?

11%

Explanation:

Average cost of automobiles in 2013 = $15,500

Average cost of automobiles now = $17,205

Change in average cost = $17,205 - $15,500

= $1,705

Rate of increase in cost is the ratio between the increase and the average cost before the increase.

Rate of increase = ($1,705/$15,500) * 100%

= 11%

The rate of increase for these automobiles between the two time periods is 11%.