A) If the distribution of sample means is bell-shaped, how do you decide whether to use a z or t test statistic? B) When estimating a standard deviation with n = 100, does the population still need to be normally distributed? C) What happens to the width of the confidence interval if the sample size increases? Choose One: Increases Decreases Stays the same
A) If the distribution of sample means is bell-shaped, how do you decide whether to use a z or t test statistic?
B) When estimating a standard deviation with n = 100, does the population still need to be
C) What happens to the width of the confidence interval if the
Choose One: Increases Decreases Stays the same
Solution :
A) Use of Z-statistic or t-statistic is depends on sample size. If sample size n is large ( >30) then z-statistic is used. If the sample size n is small ( <30) then t-statistic is used. So if the distribution of sample means is bell-shaped, whether to use z-statistic or t-statistic is depends on sample size.
B) Sample Standard deviation is estimated as , S=
Here is a mean of sample and sample is taken from normally distributed population. also given sample size n is large .
So when estimating a standard deviation with n =100 , population need to be normally distributed.
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