Q&A - P5 Math

[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

[2snoopy]

Use algebraic equations and substitution method to solve.

Qn3: Eq1: M=(1/4)R, Eq2: R+24=2(M+24)-14.
Qn1: Eq1: C-3=(1/6)G, Eq2: 1/4(G-5)=C, after solve for C and G values, substitute into Eq3: C+G
Qn2: needs time to think.

[rocklee]

Hi Tianzhu


Thank you very much for your solutions. You are a gem in this forum. I am sure many parents benefitted a lot from your selfless contribution.

Cheers

[wintay]

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:

Hi Gemini,
Thanks!!!

[tianzhu]

Hi


I'll take Q2 first because I miss my ah ma.

Best wishes.

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[tianzhu]

chokos:

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

Hi

Now
Mark’s age ------ 1 unit
Ronald’s age ------ 4 units

In 24 years’ time
Mark’s age ------ 1 unit + 24
Ronald’s age ------ 4 units + 24

Ronald age will be 14 years less than twice Mark's age.

You may use MD or work using units depending on your preference.

1 unit + 24 + 1 unit + 24 ------ 4 units + 24 + 14
1 unit ----- 5

4*5 ------ 20

Ronald is 20 years old now.

Best wishes

[tianzhu]

chokos:

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

Hi

Based on the question as worded, the answer is 62.5.

At first
Crystal marbles ----- 1 unit + 3
Glass marbles ------ 6 units

In the end
Crystal marbles ----- 1 part
Glass marbles ------ 4 parts

Again, equalise the parts or cross multiply.

(1 unit + 3)*4 ------- 6units - 5
4 units + 12 ------- 6 units – 5

2 units ------ 17
1 unit ------ 8.5

Crystal marbles ------- 11.5
Glass marbles ------- 51
Total number of marbles -------- 62.5

Best wishes

[tianzhu]

zico:

Is there a algerbra way to solve this?

Hi

Yes, there is.

Best wishes

[2snoopy]

Is primary 5 students start to learn algebraic equation in school? If yes, then can use my method.