Q&A - PSLE Math

[Chan09]

Q7. I have some red & blue ribbons in a bottle. If I add in 20 red ribbons, 60% of my ribbons are blue. If I add in another 60 blue ribbons, 75% of my ribbons are blue. How many ribbons have I in the bottle ??


Ans: 180 but I don’t understand why deduct 20 red if I use the UTM method, can this be done by model? As I got 160 if I use model?

[small]

Hi chan09,


I think the answer should be 80 red and blue ribbons in the bottle at first

[tianzhu]

Chan09:

Q7. I have some red & blue ribbons in a bottle. If I add in 20 red ribbons, 60% of my ribbons are blue. If I add in another 60 blue ribbons, 75% of my ribbons are blue. How many ribbons have I in the bottle ??


Ans: 180 but I don't understand why deduct 20 red if I use the UTM method, can this be done by model? As I got 160 if I use model?

Hi

Good Morning.

This question was earlier posted by Fat Mama on page 485 of this thread.

Please refer to the earlier discussion.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=4840

Best wishes

[tianzhu]

small:

Hi chan09,


I think the answer should be 80 red and blue ribbons in the bottle at first

Hi small

Good Morning.

Please try this question.

Mrs Lim bought some bowls and plates. If she buys another 5 bowls, there are 60% as many bowls as plates. If she buys another 9 plates, there will be thrice as many plates as bowls. How many bowls did she buy? (CHS P5 SA2 2009)

How would you interpret it and what would be your answer?

Best wishes

[alan000]

http://i42.tinypic.com/xm8n08.jpg\">

Chan09:

Q7. I have some red & blue ribbons in a bottle. If I add in 20 red ribbons, 60% of my ribbons are blue. If I add in another 60 blue ribbons, 75% of my ribbons are blue. How many ribbons have I in the bottle ??


Ans: 180 but I don't understand why deduct 20 red if I use the UTM method, can this be done by model? As I got 160 if I use model?

Dear Chan09,

Usually I get my DS to think about what remains the same or what has changed when dealing with problems sums. Also bear in mind, get your DD/DS to simplify the numbers when dealing with percentages.

[small]

tianzhu:

small:

Hi chan09,


I think the answer should be 80 red and blue ribbons in the bottle at first

Hi small

Good Morning.

Please try this question.

Mrs Lim bought some bowls and plates. If she buys another 5 bowls, there are 60% as many bowls as plates. If she buys another 9 plates, there will be thrice as many plates as bowls. How many bowls did she buy? (CHS P5 SA2 2009)

How would you interpret it and what would be your answer?

Best wishes

Hi Chan09,

For your question, it should be based on two different cases; but I could not get the solution for this. :oops:

[2DMommy]

Please help me with this question. Sorry, doesn't quite know how to attach the pic. Thank you


http://i44.tinypic.com/w2gldh.jpg

[Fat Mama]

Hi 2DMommy


DD ans as follows :

Tri ABF = 1/2 base x ht
= 1/2 x 2U x U
U sq = 25
U = 5

So AB = 10cm and CF = 5cm
Rect ACFD = 13 x 5
= 65 cm sq

[MathIzzzFun]

2DMommy:

Please help me with this question. Sorry, doesn't quite know how to attach the pic. Thank you


http://i44.tinypic.com/w2gldh.jpg

Hi

AB --> 2u
BE --> 1u
Area of triangle ABF = 25 cm2 = 1/2 x AB x BE = u x u
u = 5 cm
So, AB = 10 cm, BE = 5cm ... I think you can complete the solution

cheers.

[small]

Hi Chan09,


I misinterpreted \"If she buys another 5 bowls, there are 60% as many bowls as plates\" as 60% are bowls and 40% are plates , thats why I could not solve the question