What value of z should we use when making a 98% confidence interval for p? 1) 2.33 2) 1.75 3) It's impossible to make a 98% CI 4) 2.88

Answer: Option 1) 2.33

Step-by-step explanation:

For the 98% confidence interval we have that the area between 0 and the z score is equal to:

98% corresponds to 0.98

then the area between 0 and z is half of that:

a = 0.98/2 = 0.490

Now you can search in a table, and you will find that the z-score for this is z = 2.326

So the correct answer is 1) 2.33

where the result is rounded up.

z

- score for 98% confidence interval is

2.33

Step-by-step explanation:

How to obtain this.

Half of

0.98

=

0.49

Look for this value in the area under Normal curve table.

The nearest value is 0.4901

Its

z

value is

2.33