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A study of hedge fund investors found that their annual household incomes are normally distributed with a mean of $175,000 and a standard deviation of $25,000. (1) What percent of hedge fund investors have incomes less than $100,000? (2) What percent of hedge fund investors have incomes greater than $225,000? (3) What percent of hedge fund investors have incomes greater than $150,000?

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1. Approximately 0.14% of hedge fund investors have incomes less than $100,000.

2. The area greater than 2.00 is 1 - 0.97725 = 0.02275.

3. The area greater than -1.00 is 1 - 0.15865 = 0.84135.

1. What percent of hedge fund investors have incomes less than $100,000?

To calculate the percentage of hedge fund investors with incomes less than $100,000, we need to find the z-score of $100,000 and then use the standard normal distribution table to find the corresponding area.

z = (X - μ) / σ = ($100,000 - $175,000) / $25,000 = -3.00

Using the standard normal distribution table, we find that the area less than -3.00 is 0.00135. Therefore, approximately 0.14% of hedge fund investors have incomes less than $100,000.

2. What percent of hedge fund investors have incomes greater than $225,000?

To calculate the percentage of hedge fund investors with incomes greater than $225,000, we need to find the z-score of $225,000 and then subtract the area less than that z-score from 1 (which represents the total area under the standard normal distribution curve).

z = (X - μ) / σ = ($225,000 - $175,000) / $25,000 = 2.00

Using the standard normal distribution table, we find that the area less than 2.00 is 0.97725. Therefore, the area greater than 2.00 is 1 - 0.97725 = 0.02275. This means that approximately 2.28% of hedge fund investors have incomes greater than $225,000.

3. What percent of hedge fund investors have incomes greater than $150,000?

To calculate the percentage of hedge fund investors with incomes greater than $150,000, we need to find the z-score of $150,000 and then subtract the area less than that z-score from 1 (which represents the total area under the standard normal distribution curve).

z = (X - μ) / σ = ($150,000 - $175,000) / $25,000 = -1.00

Using the standard normal distribution table, we find that the area less than -1.00 is 0.15865. Therefore, the area greater than -1.00 is 1 - 0.15865 = 0.84135. This means that approximately 84.14% of hedge fund investors have incomes greater than $150,000.

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