Q&A - P3 Math

[MathIzzzFun]

purple05:

1. Tina needs 58 paint brushes for an art lesson. She already has 22 paintbrushes and needs to buy the rest. She went to a bookshop and found that each packet contains 8 paint brushes. What is the least number of packets of paint brushes she needs to buy if she were to have enough for the art lesson.


2. At a funfair, only groups of 8 children can enter the haunted house at a time. If there were 66 children waiting, how many groups of children will enter the haunted house? (Each child is only allowed to enter the haunted house once)

3.Mr Lim has a bag containing 9 yellow marbles & 13 green marbles. The total mass of the marbles is 136grams. The total mass of 1 yellow marble & 1 green marble is 12grams. What is the mass of 1 yellow marble?

Need help for above qns. How to draw models for these 3 qns?

Just to check, are these kind of math questions common for P3 level? I find it too difficult for them... We could solve them but it's not easy to explain ..sigh~

Hi purple05,

Yes, these are typical questions that P3 are expected to solve.

Q1 and Q2 requires the understanding of \"remainder\" concept.

Q1.
Number of paint brushes to be purchased = 58 - 22 = 36

36 / 8 = 4 R4 >> since the paint brushes come in packets of 8,
therefore number of packets to be purchased = 4 + 1 = 5

For Q3, here is the model. Hope it helps.


http://postimage.org/image/2f5lbi58k/

cheers.

[purple05]

Hi MathIzzzFun,


Thanks for ur reply. So not all problem sums can use model to explain right? I’m not sure if teacher wants them to draw model for every qn.

Q1. 36/8 = 4 R4, ans = 5
Q2. 66/8 = 8 R2, ans = 8 (the remaining 2 kids dun get to go in, am I right?
Q3. Someone used algebra to solve it… which is more complicated to unserstand…

[MathIzzzFun]

purple05:

Hi MathIzzzFun,


Thanks for ur reply. So not all problem sums can use model to explain right? I'm not sure if teacher wants them to draw model for every qn.

Q1. 36/8 = 4 R4, ans = 5
Q2. 66/8 = 8 R2, ans = 8 (the remaining 2 kids dun get to go in, am I right?
Q3. Someone used algebra to solve it.. which is more complicated to unserstand...

Hi purple05,

Yes, MD may not be the best way for some problem sums - that's why other heuristics were also taught eg. listing, looking for patterns, G&C etc. MD is introduced at pri level to solve problem sums which are normally solved using algebra.

oops.. thanks for correcting the error for Q1..
yep.. for Q2 ans =8 cos only group of 8 can enter.

cheers.

[bookwormkids]

Hi Jieheng!


Thanks for your solution. However, I don't understand your equation (basket + 54 eggs + 9 eggs = 1008g). Could you explain further pls? Thanks for your time. :D[/quote]

Basket + 63 Eggs = 1008

Basket + 54 Eggs + 9 Eggs = 1008

63 Eggs = 54 Eggs + 9 Eggs[/quote]

Thank you! I need sometimes to digest this solution and explain to my kid. :oops:

[bookwormkids]

tianzhu:

Hi


Hope this helps.

Best wishes.

http://farm6.static.flickr.com/5068/5615641596_aafabc9d7a_z.jpg\">

Hi tianzhu! Thanks for putting up the beautiful \"goli\"

[tianzhu]

bookwormkids:

Hi tianzhu! Thanks for putting up the beautiful \"goli\"

Hi bookwormkids

Good Morning.

You're welcome.

Best wishes

[tianzhu]

Hi


Hope this helps.

Best wishes.

http://farm6.static.flickr.com/5142/5617345067_e5912fd602_z.jpg\">

[bookwormkids]

tianzhu:

Hi


Hope this helps.

Best wishes.

http://farm6.static.flickr.com/5142/5617345067_e5912fd602_z.jpg\">

Hi Tianzhu, Good Morning! Thank you so much!

[bookwormkids]

I’ve a hard time explaining this question to my younger kid. Hope someone can help.


Q45)
6 cubes were taken out of Box A and put into Box B. As a result, Box B had 28 cubes. Later 4 cubes from Box B were put into Box A. Box B then had twice as many cubes as Box A. How many cubes were in Box A at first?

Many thanks.

[tianzhu]

Hi


Hope this helps.

You may use a heuristics known as \"working backwards\" to solve this question.

As usual, I've drawn more models than necessary to show the flow of events.

Best wishes.

http://farm6.static.flickr.com/5109/5618359592_09547610a4_z.jpg\">