An srs of 450 450 high school seniors gained an average of ¯ x = 20 x¯=20 points in their second attempt at the sat mathematics exam. assume that the change in score has a normal distribution with standard deviation σ = 49 σ=49 . (a) find a 95 % 95% confidence interval for the mean change in score μ μ in the population of all high school seniors. (enter your answers rounded to two decimal places.)

(15.47, 24.53)

Step-by-step explanation:

We know that the confidence interval for population mean is given by :_

, where n= sample size.

= standard deviation.

= sample mean.

z*= Critical value.

Given : n= 450

Critical value for 95% confidence = z*=1.96     [From z-value table]

Then, the 95% confidence interval will be :-

Hence, the 95% confidence interval for the mean change in score μ μ in the population of all high school seniors. : (15.47, 24.53)

answer: t=3

step-by-step explanation: