The Los Angeles Almanac Web site reports recent annual rainfall (in inches), as shown in the table.
a) Create a 90% confidence interval for the mean annual rainfall in LA.
b) If you wanted to estimate the mean annual rainfall with a margin of error of only 2 inches, how many years data would you need?
c) Do these data suggest any change in annual rainfall as time passes? Check for an association between rainfall and year.
|
Year
|
Rain(in.)
|
Year
|
Rain(in.)
|
|
1980
|
8.96
|
1991
|
21.00
|
|
1981
|
10.71
|
1992
|
27.36
|
|
1982
|
31.28
|
1993
|
8.14
|
|
1983
|
10.43
|
1994
|
24.35
|
|
1984
|
12.82
|
1995
|
12.46
|
|
1985
|
17.86
|
1996
|
12.40
|
|
1986
|
7.66
|
1997
|
31.01
|
|
1987
|
12.48
|
1998
|
9.09
|
|
1988
|
8.08
|
1999
|
11.57
|
|
1989
|
7.35
|
2000
|
17.94
|
|
1990
|
11.99
|
2001
|
4.42
|