Q&A - PSLE Math

[shurley197323]

jieheng:

At First

Red Blue
2u 3u

+ 48counters

New Ratio 1u 3u
Change to 2u 6u
(There is no change in the no. of Red counters)


Different in the ratio of after and before for blue counters = 6u - 3u =3u
3u----->48

1u----->16

No. of counters at first = 5 u = 5 * 16 = 80 (Ans)

Hi.sorry .My kid had not learn ratio yet. Got other solution?

[jieheng]

At First ,


Red [][]

Blue [][][]

After ,

Red [][]

Blue [][][] + 48

Red is 1/4 , Blue is 3/4

Red * 3 = Blue

[][] [][] [][] = [][][] + 48

[][][] = 48

[] = 16

At First ,

There are [][][]][] = 5 * 16 = 80 counters (Ans)





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[shurley197323]

Thanks, thnaks jieheng, hope you won’t feel frustrated to answer so many questions.

[jieheng]

shurley197323:

Thanks, thnaks jieheng, hope you won't feel frustrated to answer so many questions.

Hi ,

You are welcome.

No problem.

Regards,

[tianzhu]

Hi Lynn2


Ok, now the solutions to one of your earlier “coins questions”.

Usually, I solve it making some assumption.Pretend that the number of $1 coins is equal to the number of 50 cents coins, you'll have (17*1) + 15.50 more of value in Box B.

An alternative solution is MD. It hinges on “number and value” of the different coins.
Another way is to use the “Number* Value Method by working in tabulated form. This is a tweaked version of the usual “Number*Value’ table.

Hope this helps.

Best wishes

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http://farm6.static.flickr.com/5062/5557734951_9232b0d90a_z.jpg\">

[Lynn2]

Hi Tianzhu and all,


Thanks for all the helps.I will walk through with all the various way that you have provided and sure hope can clear that block in her mind.

Will post again should I failed to accomplish the mission...

Cheers
Lynn2

tianzhu:

Hi Lynn2

Ok, now the solutions to one of your earlier “coins questions”.

Usually, I solve it making some assumption.

An alternative solution is MD. It hinges on “number and value” of the different coins.
Another way is to use the “Number* Value Method by working in tabulated form. This is a tweaked version of the usual “Number*Value’ table.

Hope this helps.

Best wishes

http://farm6.static.flickr.com/5014/5557734869_1bdc3c4e23_z.jpg\">

[Lynn2]

Hi Tianzhu,


My girl is so impressed with your first model, and say wow he so smart.

But, when he looked at your xie ming ming question, try to follow your first model, and says cannot leh...she can only says why xie ming ming...the show.....

Here it goes for your question and asked can u draw it like your first model as below.Thanks.

Xie Ming Ming paid $36 for some 10 cents and 20 cents stamps. She bought 4 times as many 10 cents stamps as 20 cents stamps. How many stamps did she buy altogether?


cheers Lynn2

tianzhu:

Hi Lynn2

Ok, now the solutions to one of your earlier “coins questions”.

Usually, I solve it making some assumption.Pretend that the number of $1 coins is equal to the number of 50 cents coins, you'll have (17*1) + 15.50 more of value in Box B.

An alternative solution is MD. It hinges on “number and value” of the different coins.
Another way is to use the “Number* Value Method by working in tabulated form. This is a tweaked version of the usual “Number*Value’ table.

Hope this helps.

Best wishes

http://farm6.static.flickr.com/5014/5557734869_1bdc3c4e23_z.jpg\">

http://farm6.static.flickr.com/5062/5557734951_9232b0d90a_z.jpg\">

[tianzhu]

Hi Lynn2


For the question on Xie Ming Ming, it’s more appropriate to use “Number* Value’’ or "Grouping"

Try to look at the second MD, the one with the flower.

Please refer to my earlier post @Fri Mar 25, 2011 11:16 am

Best wishes

[jieheng]

Xie Ming Ming paid $36 for some 10 cents and 20 cents stamps. She bought 4 times as many 10 cents stamps as 20 cents stamps. How many stamps did she buy altogether?


10 cents [][] [][]

20 cents []

One set consists of 5 stamps (4 ten cents and 1 twenty cents)

Value of one set of stamp = 4 * 0.1 + 1 * 0.2 = 0.6

No. of sets of stamps = 36 / 0.6 = 60

Total no. of stamps = 60 * 5 = 300 stamps (Ans)

[ozora]

PSLE Question:

Q1) 6/14 of chairs in a hall are in rows of 13.
Half of the chairs are in rows of 7. There are 112 more chairs in the rows of 7 . The rest are stacked up. Find the total number of chairs.

Q2) Shop A has 156kg of rice while shop B has 72 kg of rice. After both shops sold an equal amount of rice, the ratio of amount of rice in Shop A to amount of rice in Shop B is 4:1. Find the amount of rice sold.