Answer:
1.415
Step-by-step explanation:
The sample standard deviation will be used, so we will build the confidence interval using the student's t-distribution.
T - interval
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 8 - 1 = 7
Now, we have to find a value of T, which is found looking at the t table, with 7 degrees of freedom(y-axis) and a confidence level of 0.90([tex]t_{90}[/tex]). So we have T = 1.415
So the answer is:
1.415
