document.write( "Question 271570: When 5 new girls joined a class, the percent of girls increased from 40% to 50%. What is the number of boys in the class \n" ); document.write( "

Algebra.Com's Answer #198927 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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When 5 new girls joined a class, the percent of girls increased from 40% to 50%.
\n" ); document.write( " What is the number of boys in the class
\n" ); document.write( ":
\n" ); document.write( "originally
\n" ); document.write( " $\"g%2F%28g%2Bb%29\"$ = .4
\n" ); document.write( "g = .4(g+b)
\n" ); document.write( "g = .4g + .4b
\n" ); document.write( "g - .4g = .4b
\n" ); document.write( ".6g = .4b
\n" ); document.write( "multiply by 10
\n" ); document.write( "6g = 4b
\n" ); document.write( ":
\n" ); document.write( "When 5 girls are added
\n" ); document.write( " $\"%28%28g%2B5%29%29%2F%28%28g%2Bb%2B5%29%29\"$ = .6
\n" ); document.write( "g + 5 = .5(g+b+5)
\n" ); document.write( "g + 5 = .5g + .5b + 2.5
\n" ); document.write( "g - .5g = .5b + 2.5 - 5
\n" ); document.write( ".5g = .5b - 2.5
\n" ); document.write( "get rid of all those decimals, multiply by 2
\n" ); document.write( "g = b - 5
\n" ); document.write( ":
\n" ); document.write( "In the original equation, replace g with (b-5)
\n" ); document.write( "6(b-5) = 4b
\n" ); document.write( "6b - 30 = 4b
\n" ); document.write( "6b - 4b = 30
\n" ); document.write( "2b = 30
\n" ); document.write( "b = 15 boys
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Check by finding the girls
\n" ); document.write( "originally
\n" ); document.write( "6g = 4(15)
\n" ); document.write( "6g = 60
\n" ); document.write( "g = 10 girls, a total class of 25
\n" ); document.write( ":
\n" ); document.write( "10/25 = .4, 40%
\n" ); document.write( ":
\n" ); document.write( "then we had 15 girls which is 50% of the class with 15 boys \n" ); document.write( "

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