Q&A - PSLE Math

[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

[tianzhu]

Beikiasu:

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.

Hi

Orchids ------ 84
Roses ------ 336 (4*84)
Difference ------ 252

An equal number of orchids and roses were added; hence the difference stays the same.

Orchids: Roses ------ 5:9
4 units ------ 252
1 unit ------ 63

Number of orchids in the end------ 5*63 -------315

Number of orchids bought ------- 315 – 84 ------231

Total number of stalks of orchids and roses ------231*2 -------462

Best wishes

[Oldschool]

Beikiasu:

Oldschool


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

Thanks

Hi

Bought equal amount of roses and orchids.
So, bought U amount of roses and U amount of orchids.
Therefore, total bought is 2U.

Regards