Question

The random variable X is best described by a normal distribution with mean of 30 and standard deviation of 6. Find the z-score that corresponds to th following X values. a. X = 21 b. X = 26 c. X = 35 d. X = 42 e. X = 50

Answer 1

The z score formula is:

Z=$\frac{X-\mu}{\sigma}$

Therefore, when:

a) X=21

Z=$\frac{21-30}{6}$ = -1.5

b)X=26

Z=$\frac{26-30}{6}$ =-0.67

c)X=35

Z=$\frac{35-30}{6}$ =0.83

d) X=42

Z=$\frac{42-30}{6}$ = 2

e) X=50

Z=$\frac{50-30}{6}$ =3.33