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 -
(click on image below to enlarge)



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 book) ----- 11/45 of book (read on 2nd day)

11/45 ----- 55 pages

1/45 ----- 55 divided by 11 = 5 pages

45/45 ----- 45 x 5 pages = 225 pages

Answer: The book had 225 pages.

*Italics in blue was amended on 14 Jan 2009 to correct typo error.