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100 juniors at a nearby private school took the ACT test. The scores were distributed normally with a mean of 22 and a standard deviation of 3

what percentage of scores are between 22 and 25?

what percentage of scores are between 16 and 28

 What percentage is less than 13

what percentage is greater than 25

approximately how many juniors scored higher than 22

and lastly how many juniors scored between 19 and 25

 

(pls note that this is my first time doing a project like this and this is new to me so i cant really read graphs well because im still learning but an explanation and answer can help,, but overall thank you for helping and answering:)

 Apr 4, 2019
edited by Nuggetguy  Apr 4, 2019
edited by Nuggetguy  Apr 4, 2019
 #1
avatar+102355 
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It the mean is 22 and the standard deviation is 3,  then  25 is one standard deviation to the RIGHT of the mean.... so 34.1%  lie between 22 and 25

 

 

16 and 28    are two  standard deviations from the mean...so  2 (34.1 + 13.6)  =  95.4%  of the scores fall between 16 and 28

 

% < 13.......13 is  3 standard deviations below the mean.....0.1% of the scores fall below this

 

% > 25.......25 is 1 standard deviation to the right of the mean....the percentage of scores > than 25  =

(13.6 + 2.1 + 0.1)  =  15.8%

 

Number who scored > 22 ....the mean is 22.....so....50% scored > than this  =  50 juniors

 

Number between  19 and 25.....these scores are one std deviation on either side of the mean....so  2 (34.1)%  =  68.2%  =  about 68 juniors

 

 

 

cool cool cool

 Apr 4, 2019
 #2
avatar+125 
+1

thank you so much for this explanation! ill be sure to take note!😎

Nuggetguy  Apr 4, 2019
 #3
avatar+102355 
0

OK.....I hope I helped....!!!!

 

 

cool cool cool

CPhill  Apr 4, 2019

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