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the number of boys in a sports club increased by 35%.

the number of girls in the club decreased by 10%.

there are now equal numbers of girls and boys.

what was the original ratio of boys:girls?

 

can someone tell me the answer and how they got it please.

 Aug 21, 2016
 #1
avatar+9665 
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Let b be the number of boys and g be the number of girls originally.

 

\((1+35\%)b=(1+10\%)g\\ \dfrac{b}{g}=\dfrac{(1+10\%)}{(1+35\%)}=\dfrac{1.1}{1.35}=\dfrac{22}{27}\\ \therefore b:g = 22:27\)

 

I divided (1+35%)g on each side of Step 1 so I get step 2. Then I simplify the fraction on the right hand side of the equal sign to make the numerator and denominator both integers. Then I used the definition of ratio to get the conclusion.

The definition: \(x:y = \dfrac{x}{y}\)

 Aug 21, 2016
 #2
avatar+9665 
0

Sorry wrong equation.

\((1+35\%)b=(1-10\%)g\\ \dfrac{b}{g}=\dfrac{(1-10\%)}{(1+35\%)}=\dfrac{0.9}{1.35}=\dfrac{2}{3}\\ \therefore b:g = 2:3\)

Same steps as the wrong equation. My mistake is just turned 1-10% into 1+10%.

 Aug 21, 2016

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