Some puzzlig answer and seek justificatn to the RoadtoPSLE
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Hi all , I using the http://road-to-psle.blogspot.com/search/label/Ratio as a useful tools to teach the 2009 Syllabus .However i encountered problem justifying certain numbers ..would appreciate if some kind soul explain some part highlighted to me ?
Labels: Mathematics, PercentageSaturday, November 17, 2007
Fuhua Primary School PSLE Math Prelim 2007 Question
Emily bought a book. On the first day, the number of pages of the book read was 25% of the number of pages unread. On the second day, she read another 55 pages of the book. As a result, the number of pages she read was 80% of the number of pages unread. How many pages did the book have?
Solution -
From the above image,
1st day ----- she read 1/5 of whole book
2nd day ----- she read 4/9 of whole book
Difference between 1st and 2nd days
(4/9 - 1/5) of whole book ----- 225 pages
11/45 of whole book ----- 225 pages
1/45 of whole book ----- 225/11 = 5 pages
Whole book ----- 5 pages x 45 = 225 pages
Answer: The book had 225 pages.<<<how does the 225 pages comes about initially ?>>>
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I believe it is a typo by the webmaster
1st day ----- she read 1/5 of whole book in total
2nd day ----- she read 4/9 of whole book in total
Difference between 1st and 2nd days
4/9 - 1/5 = 55 pages
11/45 = 55 pages
total number of pages = 225I have fed back to the webmaster through email.
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Originally posted by eagle:
I believe it is a typo by the webmaster
1st day ----- she read 1/5 of whole book in total
2nd day ----- she read 4/9 of whole book in total
Difference between 1st and 2nd days
4/9 - 1/5 = 55 pages
11/45 = 55 pages
total number of pages = 225I have fed back to the webmaster through email.
thanks eagle...i appreciate your effort to wake up that early to reply :)
