Question 1072439: Hi, could you please explain this to me?
A sample of n = 8 scores has a mean of M = 20. After one score is removed from the sample, the mean is calculated to be M = 23. The removed score must have a value greater than 20.
ANS: F
Thanks.
Answer by math_helper(2461)   (Show Source):
You can put this solution on YOUR website! Hi, could you please explain this to me?
A sample of n = 8 scores has a mean of M = 20. After one score is removed from the sample, the mean is calculated to be M = 23. The removed score must have a value greater than 20.
ANS: F
Thanks.
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That is incorrect.
The total for the 8 scores is 8*20 = 160
If I remove a score, call it k, from the 8, we get 160-k as the new total of the remaining 7 scores.
Now 160-k < 140 if k>20
and (160-k)/7 < 140/7 (=20)
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If k < 20, 160-k > 140 and (160-k)/7 > 20
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So, if M=23 after removing one score, then the removed score must have been LESS THAN 20.
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