Has the marrying age of a man changed over the years? The United States Bureau of the Census takes a formal count of everyone in the U. S. every 10 years and has provided the following data that gives the median age of an American man at the time of his first marriage.

Year
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
Median Age
25.1
24.6
24.3
24.3
22.8
22.8
23.2
24.7
26.1
26.8

Is the average rate of change zero over any ten-year period? If so, when?
a.
Yes, 1930 - 1940
b.
Yes, 1950 - 1960
c.
Yes, both 1930 - 1940 and 1950 - 1960
d.
No