Problem

In a dancing school, some students do not have a permanent dancing partner : this concerns 2/7 of the girls and ¼ of the boys. What percentage of the students has a permanent dancing partner ?

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Form is valid through November 2016

Solution

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Solution:

Let x be the number of dancing couples. Total number of girls in the dancing class is 7/5x and of boys – 4/3 x.

Thus the total number of the students is 41/15 x with 2x students having partners.

Hence 30/41 is the percentage of the the students having a permanent partner.