AP Statistics : How to find the quartiles for a set of data

Study concepts, example questions & explanations for AP Statistics

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Example Questions

Example Question #21 :Univariate Data

Obtain a normal distribution table or calculator for this problem.

Approximate the标准正态分布百分比。

Possible Answers:

Correct answer:

Explanation:

The-percentile is the value such thatpercent of values are less than it.

Using a normal table or calculator (such as R, using the command qnorm(0.9)), we get that the approximate-percentile is about.

Example Question #1 :How To Find The Quartiles For A Set Of Data

Find the first and third quartile for the set of data

Possible Answers:

Correct answer:

Explanation:

In order to find the first and third quartiles, we haave to find the 25th and 75th percentiles, respectively.

To find thepercentile, we find the product ofand the number of itemsin the set.

We then round that number如果它不是一个整数,term in the set is thepercentile.

For this problem, to find theandpercentile, we first find that there are 14 items in the set. We find their respective products to be

and

As such, theandpercentiles are the fourth and eleventh terms in the set, or

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