Question

If X = Normal (0, 4) the value of P(|X| > 2.2) is (use the normal table)

Select one:

a. 0.2713

b. 0.2321

c. 0.8438

d. 0.7286

Answer 1

Solution: We are given X follows Normal (0,4).

To find P(|X| > 2.2)

We can write P(|X| > 2.2) = P(X > 2.2) + P( X < -2.2) = 1 - P(X < 2.2) + P( X < -2.2)

= 1 - + [where is the cdf of a normal distribution with mean = 0 and standard devition = 2]

The required answer = 1 -  0.7088403 +  0.2911597 = 0.2713 [Rounded to 4 decimal places]

Ans. Option (a)