Q&A - P5 Math

[tianzhu]

Xiao Hu:

Er, who is TS? Wasn't the question from \"clblinym\"?

Hi Xiao Hu

Good Morning.

TS refers to Thread /Topic starter. It is similar in meaning to OP (Original poster).

Best wishes

[wintay]

Can anyone help to solve the problem sum below. Thanks


6 hats and 5 belts cost $150. 5 hats and 6 belts cost $147. What is the cost of one belt?

[tianzhu]

wintay:

Can anyone help to solve the problem sum below. Thanks

6 hats and 5 belts cost $150. 5 hats and 6 belts cost $147. What is the cost of one belt?

Hi

If you’re familiar with SE, you may use it.

Otherwise, you may work using MD or letters of the alphabet.

HHHHHH (6H) + BBBBB(5B) ------- 150
HHHHH(5H) + BBBBBB(6B) ------- 147

Hence, H ----- B + 3

BBBBBB + 18 + BBBBB ------- 150

BBBBBBBBBBB(11B) + 18 ------ 150

BBBBBBBBBBB(11B) + 18 ------ 150

BBBBBBBBBBB(11B) ------ 132

B ------ 12

Best wishes

[wintay]

tianzhu:

wintay:

Can anyone help to solve the problem sum below. Thanks

6 hats and 5 belts cost $150. 5 hats and 6 belts cost $147. What is the cost of one belt?

Hi

If you’re familiar with SE, you may use it.

Otherwise, you may work using MD or letters of the alphabet.

HHHHHH (6H) + BBBBB(5B) ------- 150
HHHHH(5H) + BBBBBB(6B) ------- 147

Hence, H ----- B + 3

BBBBBB + 18 + BBBBB ------- 150

BBBBBBBBBBB(11B) + 18 ------ 150

BBBBBBBBBBB(11B) + 18 ------ 150

BBBBBBBBBBB(11B) ------ 132

B ------ 12

Best wishes

Hi Thanks. Btw what is SE? And is that the only way to solve the problem sum?

[rocklee]

Hi can someone please help on the following question from SA1 2011 Nanyang:


Q1. Hui Hui had some stickers. She gave 18 stickers to her sister and 5/7 of the stickers to Mary. Then she used 3/4 of the remainder for her project and had 35 stickers left. How many stickers did she have at first?

Q2. Ali, Bala and Carl shared 90 marbles. If Ali gave 6 marbles to Bala, Bala gave 2 marbles to Carl amd after that Carl gave 1/4 of what he had then to Ali, the three boys will have the same number of marbles in the end. How many more marbles than Ali did Carl have?

Thanks.

[tianzhu]

wintay:

Hi Thanks. Btw what is SE? And is that the only way to solve the problem sum?

Hi

SE refers to simultaneous equations. It’ll be taught in secondary two.

Some primary school students are able to pick it up and solve such question through elimination method.

Usually MD or the use of alphabet are commonly used by students for such questions.They are much like a pictorial way to help students see better.

Perhaps, another way is to eliminate the hats because we want to find the cost of each belt.Again, it's quite similar to SE except we put it in a format which is more familiar to primary kids.

Best wishes

[tianzhu]

rocklee:

Q1. Hui Hui had some stickers. She gave 18 stickers to her sister and 5/7 of the stickers to Mary. Then she used 3/4 of the remainder for her project and had 35 stickers left. How many stickers did she have at first?

Hi

First question first.

You may use “Work backwards” and present your solution with MD if you prefer.

Draw a long bar, cut out a portion to show 18 stickers to her sister. Next cut 5 equal units to show 5/7 of stickers to Mary.

Cut remaining into 4 smaller parts and use 3 parts for project. The last 1 part shows 35 stickers left.

1 part ----- 35
4 parts ----- 140

2 units ------ 140 + 18 ------ 158
1 unit ------ 79

7 units ------ 7*79 ------ 553 (number of stickers at first)

Best wishes

[Gemini11]

wintay:

Can anyone help to solve the problem sum below. Thanks


6 hats and 5 belts cost $150. 5 hats and 6 belts cost $147. What is the cost of one belt?

Hi wintay here's another method, using elimination presented in a way which i think kids at P5 should be able to understand :evil:

1) Given, 6 hats and 5 belts= $150 ( mutiple all by 5)
we get... 30 belts and 25 belts= $750

2) Given also, 5 hats and 6 belts= $147 ( mutiple all by 6)
we get... 30 hats and 36 belts = $882

3) since now we know...

30 hats and 36 belts = $882
30 belts and 25 belts= $750

36- 25 belts is obviously = $882-$720
so 11 belts = $132
1 belt=$12

--------------------------------------------------

Hope it helps

Gemini11 :evil:

[tianzhu]

rocklee:

Q2. Ali, Bala and Carl shared 90 marbles. If Ali gave 6 marbles to Bala, Bala gave 2 marbles to Carl amd after that Carl gave 1/4 of what he had then to Ali, the three boys will have the same number of marbles in the end. How many more marbles than Ali did Carl have?

Thanks.

Hi

Start with the three boys in the end.

Ali ----- 30
Bala ----- 30
Carl ----- 30.

Carl received 2 marbles from Bala and gave 1/4 of what he had to Ali.

30(left) + 10 (gave) ------ 40
40 – 2 ------ 38 (at first)

Ali gave 6 marbles to Bala and received 10 marbles from Carl.

30 – 10 ------ 20
20 + 6 ------26 (at first)

36 – 26 ------ 12

Best wishes

[chokos]

Pls help to solve the following questions, thanks in advance.


Qn 1)
There are some crystal and glass marbles in a pouch. If 3 crystal marbles are removed from the pouch, the number of crystal marbles left will be 1/6 of the glass marbles left. If 5 glass marbles are removed from the pouch, the number of crystal marbles left will be 1/4 of the glass marbles left. How many marbles are there in the pouch at first?
Model Answer: 62.5

Qn 2)
Grandma had some yellow and purple sweets in the ratio 9:7. On Monday, she made 54 more yellow sweets. On Tuesday, she gave away 44 purple sweets and sold 129 yellow sweets. The number of yellow sweets to the number of purple sweets became in the ratio of 6: 5. How many yellow sweets are there in the end?
Model Answer: 258

Qn3)
Mark’s current age is 1/4 of Ronald’s. In 24 years’ time, Ronald age will be 14 years less than twice Mark’s age. What is Ronald age now?
Model Answer: 20