Assume z is a standard normal random variable. Then P(-1.96 ≤ z ≤ -1.4) equals _____.
A) .8942
B) .0558
C) .475
D) .4192

Question

Quizplus · Accepted Answer

The probability P(-1.96 ≤ z ≤ -1.4) can be found using the standard normal distribution table or a calculator. It represents the area under the standard normal curve between z = -1.96 and z = -1.4. The correct way to find this is to calculate the area to the left of z = -1.4 and subtract the area to the left of z = -1.96. Using standard normal distribution tables or calculators, the area to the left of z = -1.4 is approximately 0.0808, and the area to the left of z = -1.96 is approximately 0.025. Subtracting these gives 0.0808 - 0.025 = 0.0558.

Assume Z Is a Standard Normal Random Variable