In a situation where the standard deviation was decreased from 5.8 to 3.1, what would be the impact on the confidence interval?

It would become wider due to using the t distribution

It would remain the same as the standard deviation does impact the interval

It would become narrower due to the change in standard deviation

It would become narrower due to using the z distribution

(2) If a confidence interval is known to be (13.67, 17.53), what would be its margin of error?

0.97

1.93

3.86

13.67