Answer:
Correct formula for a 99% confidence interval for the population mean =
Step-by-step explanation:
We are provided a simple random sample of 144 items of which sample mean, xbar = 1250.25 and Standard Deviation, s = 480.
We know that follows i.e.;
follows
So, 99% confidence interval is given by ;
P(-2.61138 < < 2.61138) = 0.99 {because at 143 degree of freedom t table
gives critical value of 2.61138 at 0.5% level}
Now, after further solving this we get,
99% confidence interval for the population mean =
Since, in the question options are not given so this must be the correct formula for calculating 99% confidence interval for the population mean.