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In a class of 100, every boy had 2 girlfriends, but no girl had more than 1 boyfriend. If exactly 13 girls had no boyfriend, then how many students in the class were girls?

The answer is 71 but i dont know how to get 71?

User Kup
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2 Answers

6 votes

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User Leo Landau
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Answer:

71 girls

Explanation:

The class has 100 students.

It consists of 13 girls with no boyfriends, and the rest are "triplets" (B+2G groups)

If we subtract the 13 girls, the triplets must add up to 87 students.

The number of triplets is 87/3 = 29.

29(B + 2G) = 29B + 58G

The triplets consist of 29 boys and 58 girls with boyfriends.

No. of girls = girls with boyfriends + girls with no boyfriend

= 58 + 13

= 71

There are 71 girls in the class.

User Aaron Queenan
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