Answer: 2.
Step-by-step explanation:
Number of samples = 121
Average speed (sample mean) = 65mph
Population standard deviation = 22 mph
The standard error of the mean is:
Standard error of the mean(S.Em)
Standard error of the mean is the proportion of the population standard deviation and the square root of the sample size.
S.Em = standard deviation / √same size
S.Em = 22 / √121
S.Em = 22 / 11
S.Em = 2
