Question

8. Which of the following is not a characteristic of the normal probability distribution? Select one: a. Symmetry b. The total area under the curve is always equal to 1. c. 99.72% of the time the random variable assumes a value within plus or minus 1 standard deviation of its mean d. The mean is equal to the median, which is also equal to the mode. 10. Given that z is a standard normal random variable, what is the probability that -2.51 ≤ z ≤ -1.53? Select one: a. 0.4950 b. 0.4370 c. 0.0570 d. 0.9310 11. For a standard normal distribution, the probability of z ≥ 0 is Select one: a. 0. b. -0.5. c. 0.5. d. 1. 17.For a standard normal distribution, the probability of obtaining a z value between -2.4 to -2.0 is Select one: a. 0.4000 b. 0.0146 c. 0.0400 d. 0.5000

Answer 1

Answer 2

SOLUTION :

8.

c. 99.72% of the time the random variable assumes a value

Within plus or minus 1 standard deviation of its mean.

(ANSWER)

Explanation :

Option c is not the characteristic of a normal distribution curve. 

Within plus or minus 1 SD, 68.26% time random variable 

assumes a value.

10.

P( - 2.51 ≤ z ≤ - 1.53)

= 0.4940 - 04370. (From ND table)

= 0.0570 : Option c (ANSWER)

11.

Option c.  0.5 

12. 

P(-2.4 ≤ z ≤ - 2.0)

= 0.4918 - 0.4772. (from ND table)

= 0.0146 : Option b.  (ANSWER)