Assuming that the correlation between test X and test Y is .60 and the standard deviation of test Y is 10, if Johnny?s predicted Y score is 75 the chances are 95 out of 100 that he is one of a group of people whose scores on test Y are between
A) 59 and 91.
B) 63 and 87.
C) 67 and 83.
D) 69 and 81.

Question

Quizplus · Accepted Answer

Given the correlation (.60) and the standard deviation of test Y (10), to find the range where Johnny's score falls with 95% confidence, we use the formula for the confidence interval around the predicted score. The range provided in option A, 59 to 91, corresponds to ±2 standard deviations from the mean in a normal distribution, which covers approximately 95% of the distribution. This is a simplified explanation; in practice, calculating the exact confidence interval would require more detailed statistical formulas, but the principle of using standard deviations to estimate this range is a foundational concept in statistics.

Assuming That the Correlation Between Test X and Test Y