Percent of Data Values in 215-305 Range | Chebyshev's Theorem

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In summary, a distribution with a mean of 260 and a standard deviation of 18 will have at least 20% of the data values falling in the range of 215 to 305. This can be calculated using Chebyshev's inequality, where at least 20% of the distribution will lie between the endpoints. There is a relationship between the weight at the mean and the weight at the endpoints, with the weight at the mean being 0.2 and the weight at the endpoints being 0.4. This can be used to determine the percentage of data values within the given range.
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anita010963
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a distribution has a mean of 260 and a standard deviation of 18 What is the percentage of data values that will fall in the range of 215 to 305 please simple or explain
 
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I'm going to answer your question but I'm making no assumptions while your teacher probably wanted you to assume a normal distribution.

So 260 is exactly in the middle of the interval. Parts of the distribution outside the interval will have the least effect on the standard deviation if they are at the end points. Similarly points inside the distribution will have the least effect if they are at the mean.

Therefore, Assume the distribution has either the weight at the endpoints or at the mean. Let [tex]w_m[/tex] be the weight at the mean and [tex]w_e[/tex] be the weight at an end points. Then [tex]w_m+2*w_e=1[/tex].

Also

[tex]2* \left({305-215 \over 2} \right)^2w_e=18[/tex]

[tex]45w_e=18 <=> w_e=0.4[/tex]

and therefore:

[tex]w_m=1-2*0.4=0.2[/tex]

Therefore at least 20% of the distribution lies between the endpoints.
 

Related to Percent of Data Values in 215-305 Range | Chebyshev's Theorem

What is the relevance of determining the percent of data values in the 215-305 range?

Determining the percent of data values in a specific range can help to identify patterns and trends in the data, and can also provide information on the distribution of the data.

What is Chebyshev's Theorem and how does it relate to determining the percent of data values in a specific range?

Chebyshev's Theorem is a statistical theorem that provides a lower bound for the proportion of data values that fall within a certain number of standard deviations from the mean. It can be used to determine the minimum percentage of data values that will fall within a specific range, such as the 215-305 range.

How do you calculate the percent of data values in the 215-305 range using Chebyshev's Theorem?

To calculate the percent of data values in a specific range using Chebyshev's Theorem, you first need to calculate the mean and standard deviation of the data. Then, you can use the formula: 1 - (1/k^2), where k is the number of standard deviations from the mean that define the range. For the 215-305 range, k would be (305-215)/standard deviation.

Are there any limitations to using Chebyshev's Theorem to determine the percent of data values in a specific range?

Yes, there are some limitations to using Chebyshev's Theorem. It assumes that the data is normally distributed, so if the data is heavily skewed or has outliers, the theorem may not provide an accurate estimate of the percentage of data values in a specific range.

What other methods can be used to determine the percent of data values in a specific range?

Other methods that can be used to determine the percent of data values in a specific range include calculating the z-score and using the empirical rule. These methods also require the data to be normally distributed, but may provide more accurate estimates than Chebyshev's Theorem in certain situations.

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