Question

Questions 3-5 do not require the use of SPSS. They are practice in using the normal curve table. Question 3 On a measure of anxiety, the mean is 79 and the standard deviation is 12. a) What are the 2-scores for the following raw scores? i. 91 ii. 68 iii. 103 b) What are the raw scores for the following Z-scores? i. -1.25 ii. 0.5 iii. 2 c) What percentage of scores are above a raw score of 91? HINT: use your calculated z-score from Part a, and then refer to the normal curve table. Baraldi, PSYC3214 Statistical Methods, Spring 2020

Answer 1

a) The z scores here are computed as:

201 - 91-79 カトs

268 68 - 79 12 -= -0.9167

103 -79 2103 =.

These are the required z scores here

b) The raw scores are computed here as:

C-1.25 = -1.25 *0+u = 79 – 1.25 * 12 = 64

10.5 = 0.5*0+u = 79 +1.25 * 0.5 = 85

12 = 2*0+u = 79 +2 * 12 = 103

c) For 91, the z score is given as 1

Therefore the probability that scores are above z score of 1 is computed here as:

P(Z > 1) = 1 - P(Z < 1)

Getting it from the standard normal tables, we get:

= 1 - 0.8413

= 0.1587

Therefore 15.87% is the required percentage here.