Q&A - PSLE Math

[tianzhu]

CTong:

zara had 70 more dresses than skirts, she sold 3/4 of the dresses and 3/5 of the skirts. What fraction of the remaining clothes that Zara had were skirts?

Hi CTong

Please check your question again, looks like there is missing information.

Best wishes

[Brenda10]

tianzhu:

CTong:

zara had 70 more dresses than skirts, she sold 3/4 of the dresses and 3/5 of the skirts. What fraction of the remaining clothes that Zara had were skirts?

Hi CTong

Please check your question again, looks like there is missing information.

Best wishes

Hi Tiaznhu

This question should be from P5 SCGS SA2 2009 Qn18.

Zara has 70 more dresses than skirts. She sold 3/4 of the dresses and 3/5 of the skirts. She sold 126 more dresses than skirts. What fraction of the remaining clothes that Zara had were skirts ?

Thank you

[CTong]

Sorry, my son wrote the question for me.


Any answer for it?

[tianzhu]

Brenda10:

This question should be from P5 SCGS SA2 2009 Qn18.

Zara has 70 more dresses than skirts. She sold 3/4 of the dresses and 3/5 of the skirts. She sold 126 more dresses than skirts. What fraction of the remaining clothes that Zara had were skirts ?

Hi CTong/Brenda10

A quick one, you may avoid working with decimals by working this way.
It's helpful to draw a simple MD.

Consider skirts sold first.
Skirts sold --- 3 units

Next, consider dresses sold
Dresses sold --- 3 units + 126

Hence , one quarter of dresses ----- 1 unit+42
Hence, total number of dresses ----- 4units+168

Total number of skirts ----- 5 units

4 units + 168 ----- 5 units+70
1 unit -----98

Skirts remaining ------2*98 ------196
Dresses remaining ------- 140
Clothes remaining ------336

Skirts remaining/remaining clothes -----196/336 ------ 7/12

Best wishes

[Dharma]

Belle2011:

Dharma:

[quote=\"Belle2011\"]Dear everybody,

Happy New Year to you.

Here is another question from a worksheet given by a teacher from Just Education.

Karen is about as many days as her mother is in weeks and Karen is as months as her grandpa is in years. Karen, her mother and her grandpa are 160 years old altogether. How old is her grandpa?
(model answer: 96)

My problem is I dont really understand some parts in this question and thus unable to solve.

Thanks.

Cheers,
Belle.

Karen : Mother = a days : a weeks = a/7 weeks : a weeks = 1 : 7
Karen : Grandpa = b months : b years = b/12 years : b years = 1 : 12

Karen : Mother : Grandpa : 1 : 7 : 12
1u + 7u + 12u = 160
20u = 160
1u = 8

Grandpa's age = 12u = 12 x 8 = 96 years old

Dear Dharma,
Thanks very much for your prompt reply.

May I ask:
why consider weeks for Karen: Mother?
why consider years for Karen: Grandpa?
Also,
when you combine the 3 persons ie Karen: Mother: Grandpa, can we simply lump the ratios since Karen: Mother is originally in weeks and Karen: Grandpa is originally in years, if you know what I mean?
Thanking you in advance.

Cheers,
Belle.[/quote]What is important is to establish a relationship between Karen , her mum and her grandpa in terms of ratio based on the information given in the question. Just as how Tianzhu has demonstrated, you can even consider days to find the relationship of all 3 of them.

Karen and her mum’s ages are in a ratio of 1 : 7 and Karen and her grandpa’s ages are in a ratio of 1 : 12

Since we know that their total ages are 160 years, so that is why I added their ages in units (in years), to find Grandpa’s age.

[Andrew Lee]

Hi ...

Annie wrote her mother's age followed by her own age to form a 4-digit number. She used the diff between their ages to subtract from the 4-digit number. Then Annie obtained the number 4489. What was Annie's age ?

[INNOVATE]

Andrew Lee:

Hi ...

Annie wrote her mother's age followed by her own age to form a 4-digit number. She used the diff between their ages to subtract from the 4-digit number. Then Annie obtained the number 4489. What was Annie's age ?

Annie's age was 17. Her mother's age was 45. Difference=28.
Original 4-digit number: 4517 - 28= 4489.

[Andrew Lee]

Hi

How u know Annie’s age was 17. Her mother’s age was 45 ???

[Rockdiva]

wow…this is amazing…how do u derive that ans? why is it so difficult for a p6?

[autolycus]

If the final number is 4489 then…


1. Annie’s mum is 45 years old.

1a. If Annie’s mum was aged 44, Annie must be 10 years or below younger than her mum, but then Annie would have the numbers 89-99 for her age!

1b. If Annie’s mum was aged 46, then Annie would need to be more than 111 in difference to get 4489.

2. If Annie’s mum is 45, then the original number is 45xx.

2a. Since the final number is 4489, Annie must be at least 11 years younger than her mum (but 4500-4489 = 11 doesn’t make sense, since Annie isn’t 00 years old and surely her mum wasn’t 11 when Annie was born).

2b. If Mum - Annie = 12, original number = 4533, difference = 4533-4489 = 44.
The ‘gap’ is too big. How to make the gap smaller?

2c. If Mum - Annie = 30, original number = 4515, difference = 4515-4489 = 26.
Now that’s very close. Need to adjust by 2 years less.

2d. If Mum - Annie = 28, original number = 4517, difference = 4517-4489 = 28.

3. Yay, problem solved!