If the consumer price index for a sample of goods and services purchased in Dallas rose from 100 at the end of 1967 to x at the end of 1985, what was the average (arithmetic mean) annual increase in the index over this period?
A)(x + 100)/18
B)x/18
C)(100 − x)/18
D)(x − 100)/18
E)100x/18
A)(x + 100)/18
B)x/18
C)(100 − x)/18
D)(x − 100)/18
E)100x/18
