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

What does a rate of change of zero mean in this situation?
a.
The median age of a man at the time of his first marriage is, on the average, constant.
b.
The median age of a man at the time of his first marriage is, on the average, decreasing.
c.
The median age of a man at the time of his first marriage is, on the average, increasing.
d.
The rate of change cannot be zero in this situation.