BowenBoys Posted November 18, 2019 Report Share Posted November 18, 2019 My ten year old has this problem to solve I have X roses. 80% are white, the rest are red. I add 76 white and 48 red. Now 75% are white. What is the value of X? I have worked out the answer using a spreadsheet but he needs to show workings. Any ideas? Quote Link to comment Share on other sites More sharing options...
Jaggernaut Posted November 19, 2019 Report Share Posted November 19, 2019 Just a suggestion! Quote Link to comment Share on other sites More sharing options...
BowenBoys Posted November 19, 2019 Author Report Share Posted November 19, 2019 Yes, that's fine for me, the answer is 340. Not sure how a ten year old is supposed to show his workings though. Quote Link to comment Share on other sites More sharing options...
nickthejag Posted November 25, 2019 Report Share Posted November 25, 2019 Bit late in seeing this, but: X = W+R, where W is the no of White Roses and R is the no of Red. The ratio of 80% W means W=4R, or 0.25W=R. When you add the other roses: Total new no of White/total new no of roses = 0.75 (76+W)/((76+W)+(48+R))=0.75 ; substitute in either of the above values for R or W: (76+W)/((76+W)+(48+0.25W))=0.75; (76+W)=57+0.75W+36+0.1875W; 0.0625W=17 W=272 therefore R=272/4=68 X=272+68=340 Quote Link to comment Share on other sites More sharing options...
BowenBoys Posted November 25, 2019 Author Report Share Posted November 25, 2019 7 hours ago, nickthejag said: Bit late in seeing this, but: X = W+R, where W is the no of White Roses and R is the no of Red. The ratio of 80% W means W=4R, or 0.25W=R. When you add the other roses: Total new no of White/total new no of roses = 0.75 (76+W)/((76+W)+(48+R))=0.75 ; substitute in either of the above values for R or W: (76+W)/((76+W)+(48+0.25W))=0.75; (76+W)=57+0.75W+36+0.1875W; 0.0625W=17 W=272 therefore R=272/4=68 X=272+68=340 Correct Thanks Nick. Quote Link to comment Share on other sites More sharing options...
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