Q&A - PSLE Math

[Beikiasu]

Hi, can someone help me to solve this problem sum? SCG, 2011,

SA 1, Question 18, 5 mark. Answer $105. Thanks.

Gina, Mary and Alyssa have some money. They want to buy a handbag for their mother. Gina has $30 more than Mary.

If Gina buys the handbag, the ratio of her money left to that of Mary and Alyssa is 9:24:27 respectively.
If Mary buys the same handbag, the ratio of her money left to that of Gina and Alyssa is 1:10:9 respectively.
If Alyssa buys the same handbag, the ratio of her money left to that of Gina and Mary is 1:5:4 respectively.
What is the cost of the handbag?

[MathIzzzFun]

Beikiasu:

Hi, can someone help me to solve this problem sum? SCG, 2011,

SA 1, Question 18, 5 mark. Answer $105. Thanks.

Gina, Mary and Alyssa have some money. They want to buy a handbag for their mother. Gina has $30 more than Mary.

If Gina buys the handbag, the ratio of her money left to that of Mary and Alyssa is 9:24:27 respectively.
If Mary buys the same handbag, the ratio of her money left to that of Gina and Alyssa is 1:10:9 respectively.
If Alyssa buys the same handbag, the ratio of her money left to that of Gina and Mary is 1:5:4 respectively.
What is the cost of the handbag?

discussed on pg 573-
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=5720

cheers.

[Beikiasu]

Thanks Mathlzfun! :thankyou:


May I know where the cost of handbag --21u come from?

[MathIzzzFun]

Beikiasu:

Thanks Mathlzfun! :thankyou:


May I know where the cost of handbag --21u come from?

total amount left will be the same in case.

depending on which person buys the bag, the amount left by that person will be reduced by the number units equal to cost of handbag

gina has 30u, if she buys handbag, she is left with 9u, handbag--> 21u

alyssa has 27u, if she buys handbag, she is left with 6u, handbag --> 21u

mary has 24u, if she buys handbag, she is left with 3u, handbag --> 21u

cheers.

[Beikiasu]

Mathlzzfun :thankyou: :thankyou:

[Beikiasu]

Hi, can someone help me to solve these problem sum?

1) Joycee has some $2, $5 and $10 notes.The number of $2 notes is 25% of the total number of notes.The ratio of $5 notes to the total number of$2 and $10 notes is 2:5. Given that there are 18 more $10 notes than $2 notes, how much money does
Joycee have in all? CHIJ, 2011, Question 17, 5 mark, Answer $552.

2) A florist had 84 stalks of orchids and 4 times as many stalks of roses in her shop.After buying an equal number of orchids and roses the ratio of the number of orchids to the number of roses became 5:9.How many stalks of orchids and roses did she buy altogether? CHIIJ, 2011, Qusetion 9, 3 mark, Answer 462. Thanks.

[Beikiasu]

Hi, can someone help me to solve these problem sum?

1) Joycee has some $2, $5 and $10 notes.The number of $2 notes is 25% of the total number of notes.The ratio of $5 notes to the total number of$2 and $10 notes is 2:5. Given that there are 18 more $10 notes than $2 notes, how much money does
Joycee have in all? CHIJ, 2011, Question 17, 5 mark, Answer $552.

2) A florist had 84 stalks of orchids and 4 times as many stalks of roses in her shop.After buying an equal number of orchids and roses the ratio of the number of orchids to the number of roses became 5:9.How many stalks of orchids and roses did she buy altogether? CHIIJ, 2011, Qusetion 9, 3 mark, Answer 462. Thanks.

[Oldschool]

Beikiasu:

Hi, can someone help me to solve these problem sum?

1) Joycee has some $2, $5 and $10 notes.The number of $2 notes is 25% of the total number of notes.The ratio of $5 notes to the total number of$2 and $10 notes is 2:5. Given that there are 18 more $10 notes than $2 notes, how much money does
Joycee have in all? CHIJ, 2011, Question 17, 5 mark, Answer $552.


A.

No. of $2 is 25% or ¼ of the total number of notes.
Ratio of no. of $2 : total no. of notes = 1:4
Or,
Ratio of no. of $2 : no. of $5 and $10
= 1 : 3
Ratio of no. of $5 : no. of $2 and $ 10
= 2 : 5

B. Both ratio have the same total no. of notes. So,

$2 : $5 + $10
= 1 : 3
= 7: 21 (total = 28)

And,

$5 : $2 + $10
= 2 : 5
= 8 : 20 (total = 28)

C. Then,

Ratio of no. of $2 : no. of $5 : no. of $10
= 7 : 8 : 13
= 7U : 8U : 13U

13U -7U = 18
U = 3

So,
Ratio of no. of $2 : no. of $5 : no. of $10
= 21 : 24 : 39

D. Total $ = 21x$2 + 24x$5 + 39x$10 = $552


2) A florist had 84 stalks of orchids and 4 times as many stalks of roses in her shop.After buying an equal number of orchids and roses the ratio of the number of orchids to the number of roses became 5:9.How many stalks of orchids and roses did she buy altogether? CHIIJ, 2011, Qusetion 9, 3 mark, Answer 462. Thanks.

A. Before,

Ratio of orchids : roses
= 84 : 4x84
= 84 : 336

B. After,
Ratio of orchids : roses
= 84 + U : 336 + U
= 5 : 9

(84 + U) 9 = (336 + U)5
U = 231

C. 2U = 2x231 = 462

Regards

[Beikiasu]

Oldschool :thankyou:

[Beikiasu]

Oldschool


The second question "84 stalks of orchids …"
May i know the "2U" came from where?

Thanks