Question

In a normal distribution N(0,1), what are the two z-scores that will be the lower and upper boundaries for the middle 90 percent of the distribution?

Choose the listed values that are the closest to your calculated value!

- 1.96 and + 1.96

- 1.96 and + 1.65

- 2.58 and + 2.58

- 2.00 and + 2.58

- 1.65 and + 1.65

- 2.00 and + 2.00

Answer 1

Answer

Middle 90% means that we are left only with 10% in total

So, out of 10%, we will have 5% on lower end and 5% on the upper end

alpha = 5%/100 = 0.05

using z percentile table, check the z score corresponding to 5th percentile (for lower 5%) and z score corresponding to 95th percentile (for upper 5%)

we get

lower end z score= -1.65

and upper end z score = +1.65

option E