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I am a Primary 6 Student and have been reading your blog since P5. I would like to ask for your help in the 2 questions from Pei Hwa Presbyterian CA1 Math paper:
Paper2
Q18:
7 apples cost $4
9 oranges cost $11
James bought a total of 1000 apples and oranges for $999.
How many apples and how many oranges did he buy?
Q5:
297 digits are used to print the page numbers of a story book.
What is the number on the last page number of the story book?
Please help me as I have spent so much time trying to find the answers and still can't.
Thank you so much and happy new year.
Tuesday, February 15, 2011
Maths Qs from reader
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2 comments:
Q5 Answer:
1 to 9 have 9 digits
10 to 99 have 180 digits
100 to 135 have 108 digits
9+180+108 gives 297 digits.
Hence the number on the last page number is 135.
Q18 Answer:
Let A = total numbers of Apples
and B = total number of Oranges.
( I used B instead of O )
(A/7)4 + ( B/9 ) 11 = 999
4A/7 + 11B/9 = 999
( 36A + 77B )/63 = 999
36A + 77B = 62937 ------ (1)
B + A = 1000
A = 1000 - B ------------ (2)
Sub (2) into (1)
36( 1000 - B ) + 77B = 62937
36000 – 36B + 77B = 62937
41B = 62937 – 36000 = 26937
B = 26937/41 = 657
A = 1000 – 657 = 343
So, James bought 343 apples and 657 oranges.
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