At a Particular Academically Challenging High School,the Average GPA of a High

Multiple Choice

At a particular academically challenging high school,the average GPA of a high school senior is known to be normally distributed.After a sample of 20 seniors is taken,the average GPA is found to be 2.71 and the variance is determined to be 0.25.Find a 90% confidence interval for the population mean GPA.

A) [2.5167,2.9033]
B) [2.5261,2.3939]
C) [2.5615,2.8585]
D) [2.6358,2.7842]