Q&A - P3 Math

[jieheng]

bookwormkids:

Q1)

Basket A and B have the same mass when empty. When 63 eggs are put into Basket A, it weighs 1kg 8g. When 54 eggs are put into Basket B, it weighs 891g. What is the mass of the empty basket? [Ans: 189g]

Q2)
2 similar boxes contained some marbles. Box A with 18 marbles weighed 250g. Box B with 23 similar marbles weighed 55g more.
a) How much did one marble weigh? [Ans: 11g]
b) How much did each box weigh? [Ans: 52g]

Q3)
Basket X and Basket Y are the same mass. The total mass of Basket X together with 25 balls is 1kg 200g. The total mass of Basket Y together with 15 balls is 800g. All the balls are identical.
a) Find the mass of 1 ball. [Ans: 40g] (I keep getting 50g)
b) Find the mass of the basket. [Ans: 200g]

Pls help. Thanks.

Q1)

1kg 8 g = 1008 g

Basket + 63 Eggs = 1008

Basket + 54 Eggs + 9 Eggs = 1008

891 + 9 Eggs = 1008

9 Eggs = 1008 - 891 = 117

1 Egg = 117 /9 = 13 (g)


54 Eggs = 54 * 13 = 702 (g)


Basket + 54 Eggs = 891

Basket + 702 = 891

Basket = 891 - 702 = 189 (g)

the mass of the empty basket is 189 g (Ans)


You can use the same method to solve Q2 and Q3.

[bookwormkids]

jieheng:

bookwormkids:

Q1)

Basket A and B have the same mass when empty. When 63 eggs are put into Basket A, it weighs 1kg 8g. When 54 eggs are put into Basket B, it weighs 891g. What is the mass of the empty basket? [Ans: 189g]


Q1)

1kg 8 g = 1008 g

Basket + 63 Eggs = 1008

Basket + 54 Eggs + 9 Eggs = 1008

891 + 9 Eggs = 1008

9 Eggs = 1008 - 891 = 117

1 Egg = 117 /9 = 13 (g)


54 Eggs = 54 * 13 = 702 (g)


Basket + 54 Eggs = 891

Basket + 702 = 891

Basket = 891 - 702 = 189 (g)

the mass of the empty basket is 189 g (Ans)


You can use the same method to solve Q2 and Q3.

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.

[jieheng]

bookwormkids:

jieheng:

[quote=\"bookwormkids\"]Q1)

Basket A and B have the same mass when empty. When 63 eggs are put into Basket A, it weighs 1kg 8g. When 54 eggs are put into Basket B, it weighs 891g. What is the mass of the empty basket? [Ans: 189g]


Q1)

1kg 8 g = 1008 g

Basket + 63 Eggs = 1008

Basket + 54 Eggs + 9 Eggs = 1008

891 + 9 Eggs = 1008

9 Eggs = 1008 - 891 = 117

1 Egg = 117 /9 = 13 (g)


54 Eggs = 54 * 13 = 702 (g)


Basket + 54 Eggs = 891

Basket + 702 = 891

Basket = 891 - 702 = 189 (g)

the mass of the empty basket is 189 g (Ans)


You can use the same method to solve Q2 and Q3.

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.

[/quote]Basket + 63 Eggs = 1008

Basket + 54 Eggs + 9 Eggs = 1008

63 Eggs = 54 Eggs + 9 Eggs

[tianzhu]

Hi


Hope this helps.

Best wishes.

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

[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~

[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\"