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 Suppose that 6% of the eighth graders and 3% of the seventh graders at Washington Junior High participate in MATHCOUNTS. There are 1.5 times

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Suppose that 6% of the eighth graders and 3% of the seventh graders at Washington Junior High participate in MATHCOUNTS. There are 1.5 times as many eighth graders as seventh graders at the school. What percentage of the seventh and eighth graders, taken together, participates in MATHCOUNTS? Express your answer to the nearest tenth.

 Jul 27, 2015

Best Answer 

 #1
avatar+128475 
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Let N be the number of seventh-graders.....then, 1.5N = the number of eigth--graders....so we have

 

[.06(1.5)N + .03(N)] / [N + 1.5N]  =

 

[.09N + .03N] / [ 2.5N]  =

 

[.12N] / [2.5N]  =     ["cancel" the "N's" ]

 

.12/2.5 =  .048  =  4.8% 

 

 

  

 Jul 27, 2015

1+0 Answers

 #1
avatar+128475 
+5
Best Answer

Let N be the number of seventh-graders.....then, 1.5N = the number of eigth--graders....so we have

 

[.06(1.5)N + .03(N)] / [N + 1.5N]  =

 

[.09N + .03N] / [ 2.5N]  =

 

[.12N] / [2.5N]  =     ["cancel" the "N's" ]

 

.12/2.5 =  .048  =  4.8% 

 

 

  

CPhill Jul 27, 2015

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