+0  
 
0
733
4
avatar+1832 

 Apr 5, 2015

Best Answer 

 #1
avatar+118677 
+13

If the variance is 16 then the standard deviation is 4

49 is one standard deviation above the mean.

50% of scores are above the mean and

68%/2 = 34% are between the mean and 1 standard dev above the mean.

SO

(50-34)% = 16% of scores are above 49    

 Apr 5, 2015
 #1
avatar+118677 
+13
Best Answer

If the variance is 16 then the standard deviation is 4

49 is one standard deviation above the mean.

50% of scores are above the mean and

68%/2 = 34% are between the mean and 1 standard dev above the mean.

SO

(50-34)% = 16% of scores are above 49    

Melody Apr 5, 2015
 #2
avatar+33661 
+10

This assumes the distribution is a normal (Gaussian) one, though the question doesn't say so.  If it were a symmetrical triangular distribution with those parameters, for example, none of the displayed solutions would be right.

 

I wonder if there's a symmetrical distribution of some sort for which (b) would be the right answer!

.

 Apr 5, 2015
 #3
avatar+118677 
+10

I didn't think of that Alan, yes there must be a distribution for which B is correct. 

C and D are more than 50% so they will never  be correct!

 Apr 5, 2015
 #4
avatar+1832 
+5

Thank you all 

 Apr 9, 2015

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