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# counting

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At a particular school with 43 students, each student takes chemistry, biology, or both. The chemistry class is three times as large as the biology class, and 8 students are taking both classes. How many people are in the chemistry class?

Apr 4, 2021

#1
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Draw a venn diagram. Let there be \$x\$ students taking only chemistry and \$y\$ taking only biology. Then \$(x+8)=3(y+8)\$ and \$x+y+8=43\$. Now solve this, and the answer will be whatever \$x+8\$ is.

Apr 5, 2021
#3
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(43 + 8)/4 = 12.75 x + 3x - 9 = 43       x = 13        3x = 39

x + 3x - 5 = 43       x = 12        3x = 36

x + 3x - 8 = 43       x = 12.75          3x = 38.25       Wrong!!!

civonamzuk  Apr 5, 2021
edited by civonamzuk  Apr 5, 2021
#2
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At a particular school with 43 students, each student takes chemistry, biology, or both. The chemistry class is three times as large as the biology class, and 8( ) students are taking both classes. How many people are in the chemistry class?

It's NOT 8 !!!

It's either 5 or 9.

(43 + 5)/4 = 12              chemistry class = 3 * 12 = 36

(43 + 9)/4 = 13              chemistry class = 3 * 13 = 39

Apr 5, 2021