Q&A - P5 Math

[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.

[chokos]

Hi all,

Thanks for helping.
I need help to solve the following questions:

Q 1) Some pupils from 5K, 5L and 5M took part in a Social Studies quiz. 34 participants were from 5L and 5M. 21 participants were not from 5L and 19 participants were not from 5M. How many pupils from these 3 classes took part in the quiz? Model Answer: 37pupils

Q 2) Mrs Lee spent ½ of her money on some almond cookies and 2/5 of the remaining money on 6 slices of butter cake. Each slice of butter cake costs thrice as much as one almond cookie. How many almond cookies did she buy? Model Answer: 18 almond cookies.

Q3) Three sisters Lisa, Ming and Nora shared the cost of a present for their father. Lisa paid ¼ of the total share of Ming and Nora. Ming paid 1/9 of the total share of Lisa and Nora. Nora paid $60 more than Ming. How much did the present cost? Model Answer: $100

Q4) Jason and Kevin were given some money each. If Jason and Kevin spent $100 and $50 each day respectively. Jason would have $1300 when Kevin had spent all his money. If Jason and Kevin spent $50 and $100 each day respectively, Jason would have $3700 when Kevin had spent all his money. How much money was given to Jason at the beginning.
Model Answer: $4500