Phone calls received by a Police dept. are normally distributed. A random sample of 16 days showed that the dept. received an average of 223 phone calls per day with a sample standard deviation of 31 calls.
a. Find a 95% confidence interval for the mean number of phone calls received each day.
b. Find the margin of sampling error E
c. Find the length of the confidence interval
d. Find a point estimate for the mean.
e. Use the confidence interval found in (d) to test whether the mean # of phone calls received is 205.
f. Use the confidence interval found in (d) to test whether the mean # of phone calls received is 220
g. Without computing the 99% CI, can you draw a conclusion (still testing whether the mean # of phone calls is 220) at the 1% significance level?
h. Without computing the 99% CI, can you draw a conclusion (now testing whether the mean # of phone calls is 205) at the 1% significance level?