A random sample of size 9 is collected from a normally distributed random variable. The sample mean is 6.507 and the sample variance is 3.99. An exact 80% confidence interval for the mean of the random variable is required.How should you calculate confidence interval using quantiles from a t-distribution and with how much degree of freedom? Is it approprait to use in calculating the confidence of interval quantiles from a normal distribution?Explain and show work.