Question

Find the area under the normal curve between the values z=-2.61 and z=0.4

Round your answer to 4 decimal places.

Answer 1

0.6508

Explanation:

The standard normal distribution has a mean μ= 1 and standard deviation σ = 0

The area under the normal curve for any z value say Z i.e. P(z ≤ Z) can be read off from the Standard Normal Tables or just use a statistical calculator

Using a calculator is best
I see the lower z score as - 2.61 and the upper z score as 0.4

P(-2.61 ≤ z ≤ 0.4) = P(0.4) - P(-2.61)

P(z ≤ 0.4) = 0.65542

P(z ≤ -2.6) = 0.0045271

P(z ≤ 0.4) - P(z ≤ -2.6) = 0.65542 - 0.0045271 = 0.6507588 = 0.6508 rounded to 4 decimal places

(Note: some calculators are able to directly compute the area between two z values)