Mrs Yu paid $16.20 for some eraser and pencils. An eraser cost 15 cents and a pencil cost 45 cents. She bought 12 more pencils than erasers. How many erasers did she buy?
Solution
1 eraser ----- $0.15
1 pencil ----- $0.45
1 set (of 1 eraser, 1 pencil) ----- $0.60
She bought -----
Unknown number of sets + 12 pencils ----- $16.20
(? x $0.60) + (12 x $0.45) ----- $16.20
(? x $0.60) + $5.40 ----- $16.20
? x $0.60 ----- $16.20 - $5.40 = $10.80
? ----- $10.80 divided by $0.60 = 18 (sets)
18 sets ----- 18 erasers
Answer: She bought 18 erasers.
Tuesday, April 14, 2009
Rosyth Sch 2006 PSLE Math Prelim Q43
Subscribe to:
Post Comments (Atom)
10 comments:
lousy method! USE HEURISTICS
Hi anon@0313
Please do not hide under the veil of anonymity and pass discouraging remarks.
Mr Song's blog is very useful for those PSLE kids who do not have the previleges of tuition.Not every student can afford to get external help.
Mr Song helps to provide meaningful materials free for which we should be grateful.
If you have better solutions, please share.
hey, Mr Song is your uncle, is it? Why so protective? The methods is so confusing and will make students even more confuse! Share? Why?
hey, Mr Song is your uncle, is it? Why so protective? The methods is so confusing and will make students even more confuse! Share? Why?
Hi
To many less privileged kids, Mr Song is like a kind uncle who shares his resources unselfishly. He didn’t claim they are the best solutions, but for those kids without external help, they are good enough. For those who are more blessed with alternative resources, please be more tolerant and understanding towards others.
Mr Song, we look forward to more regular updates in your blog.
Hi
To many less privileged kids, Mr Song is like a kind uncle who shares his resources unselfishly. He didn’t claim they are the best solutions, but for those kids without external help, they are good enough. For those who are more blessed with alternative resources, please be more tolerant and understanding towards others.
Mr Song, we look forward to more regular updates in your blog.
any relative again!
Number Cost Total Cost
Eraser 1u 15 15u
Pencils 1u+12 45 45u+540
Total 60u+540
60u+540=1620
60u= 1080
1u = 18
the anonymous person who said this method is lousy, then wat other method is there? Care to share?
can anyone tell me why can't the following method work?
12x$0.45=$5.40
$16.20-$5.40=$10.80
$10.80/2=$5.40
$5.40/$0.15=36 erasers
pls tell me pls thx a lot! :D
Post a Comment