Data on effective life of a particular light bulbhave been collected and it is known that itapproximatelyfollows a normal distribution. Find confidence intervals on the mean for the following conditions:(a)Observations are: 97, 95, 99, 101, 99, 98, 95, 96, 96, 94; Population standard deviation is known to be 2; confidence level is 90%; two-sided(b)Observations are: 97, 95, 99, 101, 99, 98, 95, 96, 96, 94; Population standard deviation is known to be 2; confidence level is 90%; one-sided (upper)(c)Observations are: 97,95, 99, 101, 99, 98, 95; Population standard deviation is unknown; confidence level is 90%; two-sided(d)Forty fiveobservations are available with sample mean of 98and sample standard deviation of1.5; Population standard deviation is unknown; confidence level is 90%; two-sided