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Math Challenge I-A + I-B Counting and Probability

 
 
LiangNeo的头像
Math Challenge I-A + I-B Counting and Probability
LiangNeo - 2019年08月5日 Monday 10:35
 

Lecture 9, Problems 9.10 c and 9.10 b

for 9.10 b, I got 84.9 because 60+64+78+80+90+92+94+95+97+99=849, and $\frac {849}{10}$=84.9    The answer says that it is 85

for 9.10 c, I got 86.6 or $\frac {433}{5}$ because the new mean is $\frac {849+450}{15}$=86.6    The answer says that it is $\frac {1300}{15}$

 
ReynosoDavid的头像
Re: Math Challenge I-A + I-B Counting and Probability
ReynosoDavid - 2019年08月7日 Wednesday 17:56
 

You are correct. The way the problem was written the sum of all the grades is $849$. This was a typo, as we intended the sum to be $850$ to make the calculations easier. The second to last grade should have been $98$, not $97$. 

Thanks for letting us know!

 
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