00:01
For this problem, we want to find the average rate of change in advertising expenditures over the given interval.
00:06
So for part a, we have an interval from 1950 to 1970.
00:12
So we have f of 1970 minus f of 1950 over 1970 minus 1970 minus 1950.
00:27
And if we plug in the values from the graph, we get 19 ,000.
00:33
550 minus 5 ,700 over 1970 minus 1950, which is 20.
00:43
And if we subtract, we get 13 ,850 over 20, which is $692 .5 dollars per year are units.
01:02
So that's our answer to part a.
01:03
For part b, our interval is from 1970 to 1980.
01:09
So we have f of 1980 minus f of 1970 over 1980 -over 1980 -1980 minus 1980 -over 1980 -minus 1980 -over 1980 -minus 1970.
01:23
So if we plug in our values, we get 54 ,780, minus 19, 550, over 9 ,550 over 9 ,000.
01:36
180 minus 1970, which is just 10...