Question: Units of Standard Deviation

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Comment on Units of Standard Deviation

When the question asks for the numbers that are more than half the unit of standard deviation, would not it be the numbers that are greater than 6.9 ? Why do choose the numbers that fall below 6.9? Please reply. Thanks.
greenlight-admin's picture

The question is asking us to identify all values that are more than 0.5 units of standard deviation BELOW the mean.

0.5 units of standard deviation BELOW the mean = 9 - (0.5)(4.2) = 6.9

0.6 units of standard deviation BELOW the mean = 9 - (0.6)(4.2) = 6.48. This means that 6.48 is more than 0.5 units of standard deviation BELOW the mean

Likewise, 0.7 units of standard deviation BELOW the mean = 9 - (0.7)(4.2) = 6.06. This means that 6.06 is more than 0.5 units of standard deviation BELOW the mean

Does that help?

So, What happen with numbers 14 and 18 are? Why are they not included as part of the answer ? if they are numbers > 0.5 units of SD in the right side.
greenlight-admin's picture

The question does not ask us to identify values that are more than 0.5 units of SD AWAY from the mean. It asks us to identify values that are more than 0.5 units of SD BELOW (less than) the mean

Thanks so much. Probability, I didn't pay attention to the word "below". So, Everything is clear now.

im really amazed with ur videos and prompt replies ...thnx a lot.
greenlight-admin's picture

Glad to help!

Hi! Can you use a proportion for the units of SD. For example, 1 unit of SD/4.2 SD = 0.5 units of SD/x SD to get 2.1?
greenlight-admin's picture

Most definitely!

Great exercise!. At first I answered 6, but those are the number below the mean. The answer ask for the numbers 0.5 units of SD below of the mean.

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