I'M LOST ON THIS COULD SOMEONE HELP ME PLEASE!!!!!!!

Question

Bewildered!!!

 

Find the critical value z a/2 that corresponds to the given confidence level.
95%

z _a/₂ = ? (Round to two decimal places as needed.)

Answer 1

Hi Wendy,

 

If you are permitted to use a calculator like the TI-83( a popular model), press 2nd and then 3: InvNorm and enter half of the 5% which is .025 and enter. This will give you -1.96 rounded to two places. The other 2.5% will correspond to a positive 1.96

Answer 2

Hi Wendy,

 

 the critical z value that corresponds to 95% confidence level is the value in which the other 5% of the data is distributed evenly amongst the two tails of the normal distribution with mean 0 and variance 1. So, you must look at the normal 0,1 distribution and see which values on the x-axis make each tail have 0.025, or 2.5% of the data. This value, the z-value, turns out to be + or - 1.96, depending on whether you're looking at the left tail or right tail. Hope this helps.

 

-Sam