Question

(1 point) Justin is interested in buying a digital phone. He visited 9 stores at random and recorded the price of the particular phone he wants. The sample of prices had a mean of 368.73 and a standard deviation of 31.79.

(a) What t-score should be used for a 95% confidence interval for the mean, μμ, of the distribution?
t* =

(b) Calculate a 95% confidence interval for the mean price of this model of digital phone:
(Enter the smaller value in the left answer box.)
_______________ to___________________

Answer 1

(a)

SE = s/

= 31.79/

= 10.5967

= 0.05

ndf = 9 - 1 = 8

From Table, critical values of t^* = 2.3060

So,

Answer is:

2.3060

(b)

Confidence Interval:

368.73 (2.3060 X 10.5967)

= 368.73 24.4360

= ( 344.2940 ,393.1660)

So,

Answer is:

344.2940   to 393.1660