The grade point averages (GPA) of 15 randomly selected college students are 2.3, 3.3, 2.6, 1.8, 0.2, 3.1, 4.0, 0.7, 2.3, 2.0, 3.1, 3.4, 1.3, 2.6, 2.6 1. The sample mean is (Round to one decimal place)...

I need help with numbers 4, 5, and 8. Thank you so much you guys are awesome!

Extracted text: The grade point averages (GPA) of 15 randomly selected college students are 2.3, 3.3, 2.6, 1.8, 0.2, 3.1, 4.0, 0.7, 2.3, 2.0, 3.1, 3.4, 1.3, 2.6, 2.6 1. The sample mean is (Round to one decimal place) 2. The sample standard deviation is (Round to one decimal place) 3. The sample size is 4. The degree of freedom for the Studentized version of the sample mean is 5. The point estimate for the mean GPA of ALL students at this college is 6. The t-value for a 99% confidence interval is t D 7. The Margin of error for a 99% confidence interval for this sample is (Round to one decimal place) 8. The 99 % confidence interval estimate of the mean GPA of students at this college is (Round to one decimal place) 9. The sample size is needed in order to obtain a margin of error of no more than 0.5 is (Must be a whole number)