Q&A - PSLE Math

[tianzhu]

Chan09:

Appreciate some help

A had a total of 2050 black and red marbles. He lost 3/5 of his black marbles and bought 150 red marbles. As a result the no. of red marbles he had was 1/4 of the remaining black. How many more black than red marbles he had at first?
Ans: 1950

Hi

This question was discussed in an earlier post.

Please refer to solution by MathIzzzFun.

Best wishes

http://i53.tinypic.com/2vj4ozo.jpg\">

[stary]

Hi all,


Have a question to ask.

Azman had 25% more marbles than Chongfu. Chongfu had 60% more marbles than Bala. During a game, Azman and Bala lost some marbles to Chongfu in the ratio 3:1. In the end, Azman and Bala had 780 and 480 marbles left respectively.

How many marbles did Azman have at first?

[MathIzzzFun]

stary:

Hi all,


Have a question to ask.

Azman had 25% more marbles than Chongfu. Chongfu had 60% more marbles than Bala. During a game, Azman and Bala lost some marbles to Chongfu in the ratio 3:1. In the end, Azman and Bala had 780 and 480 marbles left respectively.

How many marbles did Azman have at first?

Hi

ratio -
Azman : Chongfu =125: 100 = 5:4
Chongfu : Bala = 160 : 100 = 8: 5
so, Azman : Chongfu : Bala = 10 : 8 : 5

Before losing the marbles,
Azman : Bala = 10 : 5 = 2u : 1u

Azman and Bala lost marbles in the ratio of 3:1 and had 780 and 480 left respectively.

Azman: Bala = 2u-780 : 1u-480 = 3:1
so 2u -780 = 3u - 1440, 1u = 660

at first, Azman had 2u = 2x660 = 1320 marbles.

cheers.

[TT2]

Hi I have another qn to ask…


In Jan, 80% of the members in a golf club were men. In jun, after 55 men had left and 75 women had joined the club, the % of the women increased to 40%. How many members were there in the golf club in Jan?

Thank you

[MathIzzzFun]

TT2:

Hi I have another qn to ask...


In Jan, 80% of the members in a golf club were men. In jun, after 55 men had left and 75 women had joined the club, the % of the women increased to 40%. How many members were there in the golf club in Jan?

Thank you

Hi

In Jan, ratio of men : women : 80:20 = 4u:1u ** total 5u
after 55 men left, and 75 women joined,
ratio of men : women
= 4u - 55 : 1u + 75
= 60 : 40
= 3 : 2

so, 8u - 110 = 3u + 225
5u = 335

Members in Jan = 5u = 335

cheers.

[stary]

Thanks MathIzzzFun for your prompt reply!

[Daddy]

Hi,


Need help on this question? Thanks

John had 1.5m of copper wire. He cut some of the wire to bend into the shape shown in the figure below. In the figure, there are 6 equilateral triangles and the length of XY is 19 cm. How much of the copper wire was left?

http://i55.tinypic.com/a2q0rs.jpg\">

Thanks

[stary]

Daddy:

Hi,


Need help on this question? Thanks

John had 1.5m of copper wire. He cut some of the wire to bend into the shape shown in the figure below. In the figure, there are 6 equilateral triangles and the length of XY is 19 cm. How much of the copper wire was left?

http://i55.tinypic.com/a2q0rs.jpg\">

Thanks

Hi!

Used -> 5 x 19 = 95cm
Left -> 150cm - 95cm =55cm

Best Regards

[TT2]

Hi MathIzzzfun,


Thanks for your help. Noticed that e cross-multiply way is sometimes used to solve e ratio problems n sometimes e model method can be used. My son is not familiar on e 1st method. When do we use e cross multiply method or die die must use this? Eg. There is movement of e items???? :? Pls help...... :imdrowning:

Thanks a lot

[christina soh]

TT2:

Hi MathIzzzfun,


Thanks for your help. Noticed that e cross-multiply way is sometimes used to solve e ratio problems n sometimes e model method can be used. My son is not familiar on e 1st method. When do we use e cross multiply method or die die must use this? Eg. There is movement of e items???? :? Pls help...... :imdrowning:

Thanks a lot

Hi MathIzzzFun,

What is your answer for Q14 of Paper 1 (math) of the following school?

http://www.orlesson.org/orp/09Ma/2009-P6-Math-SA2-PLMGS.pdf