The price of a box of chalk has increased from $.89 to $1.39 over a ten-year period. What index number would represent the change in price over the ten-year period?

Question

Quizplus · Accepted Answer

The index number representing the change in price is calculated by taking the new price, subtracting the old price, dividing by the old price, and then multiplying by 100 to get a percentage. So, $\frac{1.39 - 0.89}{0.89} \times 100 = 56.2$. Adding this to 100 (to account for the original price as the base of 100), we get 156.2.

The Price of a Box of Chalk Has Increased from $.89