A sample of 500 evening students revealed that their annual incomes were normally distributed with a mean income of $50,000 and a standard deviation of $4,000. What is the income that separates the top
25% from the lower 75% of the incomes?

Question

Quizplus · Accepted Answer

To find the income that separates the top 25% from the lower 75%, we need to find the 75th percentile of the normal distribution. Using the Z-table, the Z-score for the 75th percentile is approximately 0.675. Using the formula: Income = Mean + (Z-score * Standard Deviation), we get: $50,000 + (0.675 * $4,000) = $52,680.

A Sample of 500 Evening Students Revealed That Their Annual