Հարց 10

The values 4, 6, 8 and 10 have a mean of 7, and a fifth value of 7 is then added to the set. Which statements about the new set of five values are true? Select all that apply.

Adding a fifth value must change the mean.
The total of the five values is 35.Ճիշտ պատասխան
The mean of the five values rises to 7.5.
The mean of the five values is 8.75, because 35 is divided by 4.
The mean of the five values is still 7.Ճիշտ պատասխան

Բացատրություն

The original four values total 28, so adding a fifth value of 7 makes the total 35, and 35 divided by 5 values gives 7 once more. An extra observation only moves a mean when it differs from the current mean, so a value that already equals 7 leaves the balance point exactly where it was.

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