Hey I need to solve these 3 problems and I dont understand the formula's is just not clicking.
1.For this problem i need to construct the 90% and the 95% confidence intervals for the population mean and which one is wider.
From a random sample of 36 days in a recent year, the closing stock prices for hasbro had a mean of $19.31 and a standard deviation of $2.37
2.For this problem I need to construct the indicated confidence interval for the population mean u using (a) a t-distribution. (b) If you had a incorrectly used a normal distribution, which interval would be wider?
c= .95, x= 13.4, s= 0.85, n=8
3. Assume the variable is normally distruibuted and use a t-distribution to construct a 95% confidence interval for the population mean u, and what is the margin error of u?
In a random sample of five microwave ovens, the mean repair cost was $75.00 and the standard deviation was $12.50
I really need help with these problems i keep trying to get the formulas down but nothing sticking in my head when it come to confidence intervals. Thanks in advance to whom ever helps me.