Which of the following would produce a narrow interval than 90% confidence interval computed above?
(a) Measure the heights of a random sample of 50 6-year old girls.
(b) Measure the heights of a random sample of 10 6-year old girls.
(c) Computed 95% confidence interval rather than a 90% confidence interval
(d) Computed 99% confidence interval rather than a 90% confidence interval
(e) None of the above
