psychology

Given IQ scores are approximately normally distributed with a mean of 100 and standard deviation of 15, the proportion of people with IQs above 130 is:

• 95%

• 68%

• 5%

• 2.5%

Randomly assigning treatment to experimental units allows:

• population inference

• causal inference

• both types of inference

• neither type of inference

A national random sample of 20 ACT scores from 2010 is listed below. Calculate the sample mean and standard deviation.

29, 26, 13, 23, 23, 25, 17, 22, 17, 19, 12, 26, 30, 30, 18, 14, 12, 26, 17, 18

• 20.50, 5.79

• 20.50, 5.94

• 20.85, 5.79

• 20.85, 5.94

Provided that the ACT is reasonably normally distributed with a mean of 18 and standard deviation of 6, determine the proportion of students with a 33 or higher.

• 0.0062

• 0.0109

• 0.0124

• 0.0217