Question

A survey was taken of 28 students about how long they spend on PSY 230 homework. The results were approximately normally distributed with a mean of 13 hours and a standard deviation of 2 hours. Construct a confidence interval at 90%. Round your answers to two decimal places. _______ +/- _________

Answer 1

Solution :

Given that,

= 13

= 2

n = 28

90% confidence level the z is ,

= 1 - 90% = 1 - 0.90 = 0.10

/ 2 = 0.10 / 2 = 0.05

Z_/2 = Z_0.05 = 1.645

Margin of error = E = Z_/2* ( /n)

= 1.645 * (2 / 28)

= 0.62

At 90% confidence interval is,

- E < < + E

-+E

13-+0.62

< <

(, )