A random sample of n measurements was selected from a population

A random sample of n measurements was selected from a population with unknown mean μ and standard deviation σ. Calculate a99% confidence interval forμfor each of the following situations:

(a)   n=85, x¯=23.8, s=3.75 
 ≤μ≤ 

(b)   n=120, x¯=62.7, s=4.52 
 ≤μ≤ 

(c)   n=80, x¯=50.6, s=2.67 
 ≤μ≤ 

(d)   n=85, x¯=91, s=2.73 
 ≤μ≤