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## Comment on

Units of Standard Deviation## When the question asks for

## The question is asking us to

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

## The question does not ask us

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,

## im really amazed with ur

## Glad to help!

Glad to help!

## Hi! Can you use a proportion

## Most definitely!

Most definitely!

## Great exercise!. At first I

## how do you determine 6 as the

7.6 below , 12, mean 16.4 above.

## Tuttiam52 isn't saying that

Tuttiam52 isn't saying that the correct answer is 6.

With "Units of Standard Deviation (SD)" questions, we often look at units of SD ABOVE the mean and units of SD BELOW the mean.

This question asks for 0.5 units of SD BELOW the mean.

So, we must SUBTRACT 2.1 from the 9 (the mean)

For more on this see: https://www.greenlighttestprep.com/module/gre-statistics/video/808

## Thank you so much for the

## Thanks for the kind words,

Thanks for the kind words, Reetika!

## Hi Brent,

Thank you very much for this explanation!

I have a question, if they would ask us to find all values that are 0.5 standard deviation below the mean, meaning between 6.9 and 9.

The values are like this: 7,7,7,8,8,8

Should we include 9 as well or not? Thanks

## If the question asked "find

If the question asked "find all values that are 0.5 standard deviations BELOW the mean", then the ONLY value that satisfies that condition is 6.9, since 6.9 is 0.5 standard deviations below the mean.

If the question asked "find all values that are LESS THAN 0.5 standard deviations BELOW the mean", then the values that satisfy that condition are 7,7,7,8,8,and 9.

9 work because 9 is 0 standard deviations below the mean.

Cheers,

Brent

## Thanks Brent now it is clear!