The following table shows total military and arms trade expenditure for a certain country in 2000, 2006, and 2012.

Year t (year since 2000)	0	6	12
Military Expenditure C(t) ($ billion)	330	560	620

(a)

Compute the average rate of change of C(t) over the period 20062012 (that is, [6, 12]). Be sure to state the units of measurement. HINT [See Example 1.]

---Select--- years billion dollars billion dollars per year

Interpret the average rate of change.

This country's military expenditure increased at an average rate of about ---Select--- years billion dollars billion dollars per year between 2006 and 2012.

(b)

Compute the average rate of change of C(t) over the period [0, 12]. Be sure to state the units of measurement. HINT [See Example 1.] (Round your answer to two decimal places.)

---Select--- years billion dollars billion dollars per year

Interpret the average rate of change. (Round your answer to two decimal places.)

This country's military expenditure increased at an average rate of about ---Select--- years billion dollars billion dollars per year between 2000 and 2012.