Asample of a given size is used to construct a 95% confidence interval for the population mean with a known population standard deviation. if a bigger sample had been used instead, then the 95% confidence interval would have been and the probability of making an error would have been

a. wider; smaller

b. narrower; smaller

c. wider; unchanged

d. narrower; unchanged

Option b is right

Step-by-step explanation:

Given that a sample of a given size is used to construct a 95% confidence interval for the population mean with a known population standard deviation.

Now let us assume for no change in std deviation only n increases

Since margin of error is inversely proportional to square root of n, we get as n increases margin of error decreases and as a result the width of confidence interval would decrease.

This will again ensure that type I error decreases.

So correct option would be

narrower: SMALLER

-2

7 - 9 = -2

reversed:

-2 + 9 = 7