The Intelligence Quotient (IQ) test scores are normally distributed with a mean of 100 and a standard deviation of 15.
i. What is the probability that a person would score 130 or more on the test?
ii. You enrolled in a class of 25 students. What is the probability that the class' average IQ exceeds
130?
A) 0.0228, 0.4987
B) 0.4772, 0.300
C) 0.4772, 0.0026
D) 0.0228, approximately zero
E) None of the choices are correct

Question

Quizplus · Accepted Answer

The probability of scoring 130 or more is found using the Z-score formula, resulting in a probability of 0.0228. For the class average, the standard error is smaller, making it extremely unlikely for the average to exceed 130, hence approximately zero probability.

The Intelligence Quotient (IQ) Test Scores Are Normally Distributed with a Mean