Q&A - PSLE Math

[dido]

Hi,


This is P6 question. Sorry, don’t know which section to post.

I have no answer for this.

Cheers

[Dharma]

dido:

[Moderator's note: Topics merged.]


Mr Tan had some apples and oranges in his shop. 30% of the fruits were oranges. He sold 70 apples and bought another 170 oranges. Then 65% of the fruits were oranges. How many did he have at first?

Who can help? Thanks!

http://www.postimage.org/

[xpozay]

dido:

Hi,


This is P6 question. Sorry, don't know which section to post.

I have no answer for this.

Cheers

I believe this is a P5 question. I saw very similar questions in my daughters P5 book that her tutor uses.

[tianzhu]

Hi Dharma


I am wondering why you used units and parts for the number of people. For the number of adults and children, we are using the same measures to indicate the ratio representing the number of adults to the number of children. Likewise for the price of tickets, we are using the same units of measurement to represent the dollar values of the tickets.

How do you arrive at 1p/ (1u+1p) = 3/8?

This is not an easy question as students have to have clear understanding of the differences between the units representing quantity and those representing the dollars values.

Please help to explain.

[tianzhu]

Tang:

1 Adult unit --> 21 - 2 x 18 = 5 parts

So 1 Child unit --> 8 - 5 = 3 parts

Child / Total = 3/(3+5) = 3/8

Hi Tang

How do you get (2X18)?

[Tang]

tianzhu:

Tang:

1 Adult unit --> 21 - 2 x 18 = 5 parts

So 1 Child unit --> 8 - 5 = 3 parts

Child / Total = 3/(3+5) = 3/8

Hi Tang

How do you get (2X18)?

Sorry Uncle Tianzhu,

There is a typo error. It should be 8 and not 18.

1 Adult unit --> 21 - 2 x 8 = 5 parts

I have amended the post.

[Dharma]

tianzhu:

Hi Dharma


I am wondering why you used units and parts for the number of people. For the number of adults and children, we are using the same measures to indicate the ratio representing the number of adults to the number of children. Likewise for the price of tickets, we are using the same units of measurement to represent the dollar values of the tickets.

How do you arrive at 1p/ (1u+1p) = 3/8?

This is not an easy question as students have to have clear understanding of the differences between the units representing quantity and those representing the dollars values.

Please help to explain.

Sorry bro,

Used units and parts to represent ratio of adults to children but we were not given that info.

The ticket price/fare and costs of tickets – insert $ to show that it has dollar value.

But ratio of 8/21 … the denominator is actually the number of dollars of the tickets (So NO $ sign reqd)

1u + 1p = Total no. of tourist

1u + 1p/ (3u + 2p) = 8/21
Cross multiplying
3u = 5p

1p/1u = 3/5 (Child : Adult ratio = 3:5)

Therefore; child : tourist ratio = 3: 8
Fraction of tourist who were children = 3/8




http://www.postimage.org/

[James Ang]

Practise more speed and circle questions this year.



Car A left Town X for Town Y at the same time when Car B left Town Y for Town X. The average speed of Car A was 56 km/h and the average speed for Car B was 72 km/h. The two cars passed each other at a point 24km from the midway of the two towns. What is the distance between Town X and Town Y?

[tianzhu]

Thank you for your help.


http://www.wendykoh.com/08/primary6-swastikasa2-maths.pdf

For Q47, what is your answer for Q47(c)?What is the relationship between the numbers?

[Dharma]

tianzhu:

Thank you for your help.


http://www.wendykoh.com/08/primary6-swastikasa2-maths.pdf

For Q47, what is your answer for Q47(c)?What is the relationship between the numbers?

Hi Tianzhu,

Hope this helps

c)

Pattern 1 = 5 or [5 x 1]
Pattern 2 = 12 = 5 + 7 or [6 x 2]
Pattern 3 = 21 = 5 + 7 + 9 or [7 x 3]
Pattern 4 = 32 = 5 + 7 + 9 + 11 or [8 x 4]
.
.

Pattern N = (N+ 4) x N = 285

Use Guess and check
19 x 15 = 285 (Pattern 15)