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The mean price for a home in a Florida county is $125,000. The standard deviation for the same sample is $23,000. What percentage of homes in the county are valued over $100,000? Use the Standard Normal Probabilities table to find your answer. Enter your answer with two places.

I keep getting 86.15%
The answer is supposed to be 86.21%

I am not sure what I did wrong so please explain what you did.

User Carlotta
by
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1 Answer

5 votes

Solution: There is nothing wrong with your calculation's. But the question wants to round the z score to two decimal places.

Let me show you how to get 86.21%.

We are given:


\mu=125,000


\sigma=23,000

We have to find
P(x>100,000)

Using the z-score formula, we have:


z=(x-\mu)/(\sigma)


=(100,000-125,000)/(23,000)


=-1.09 rounded to two decimal places

Now we have to find
P(z>-1.09)

Using the standard normal table, we have:


P(x>100,000)=P(z>-1.09) = 0.8621 rounded to 4 decimal places


=86.21\%

Therefore, the percentage of homes in the county that are valued over $100,000 is 86.21%

User Nastaran Mohammadi
by
7.6k points

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