When the sample size n is large,the 90% confidence interval for is
A) ± 1.96SE( ).
B) ± 1.64SE( ).
C) ± 1.64 .
D) ± 1.96.

Question

When the sample size n is large,the 90% confidence interval for  is
A) ± 1.96SE( ). 
B) ± 1.64SE( ). 
C) ± 1.64 . 
D) ± 1.96.

Quizplus · Accepted Answer

When the sample size is large (n > 30), we use the z-distribution to calculate the confidence interval. 
For a 90% confidence interval, we use a z-value of 1.64. 
Thus, the correct formula for the confidence interval is option B: 
11eab146_bd39_a54e_896a_77ae1b9c5c8f_TB2833_11 ± 1.64SE(
11eab146_bd39_a54f_896a_cf16cf6fd26b_TB2833_11 ).
Option A uses a z-value of 1.96 which is appropriate for a 95% confidence interval, not 90%. Option C is not a valid formula for a confidence interval as it is missing the standard error term. Option D is incomplete and does not provide a formula for calculating the confidence interval.

When the Sample Size N Is Large,the 90% Confidence Interval