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Andrew has these marks: English 82%, French 75%, History 78%, Science 80%

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Andrew has these marks: English 82%, French 75%, History 78%, Science 80%

a) What mark will Andrew need in math if he wants his mean mark to be each percent?

i) 80% ii) 81% iii) 82%

b) Is it possible for Andrew to get a mean mark of 84% or higher? Justify your answer.

Guest Feb 15, 2017
edited by Guest  Feb 15, 2017
#1
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a)

i - In order for Andrew to average 80% in 5 subjects, he would have to score 85% in Math.

ii-...................................................81%.............................................................90% .............

iii-..................................................82%..............................................................95%..............

b) If the maximum mark is 100%, then it is NOT possible for Andrew to get an average of 84%, since he would need a score of 105% in Math, which I assume is not allowed.

Guest Feb 15, 2017
#2
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Here's  a (i)   .....the other two are worked the same way

Average  = 80    ...so.....

[ 82 + 75 + 78 + 80 + ? ]  / 5  = 80     multiply by 5

82 + 75 + 78 + 80 + ?  = 400

315 + ?  = 400

?  =  400 -  315  =   85 is the % he needs

b   84 * 5  =  420........he only has 315...so...he needs  105 (%)  on the last test.....impossible

CPhill  Feb 15, 2017