Q&A - PSLE Math

[tianzhu]

Treelodge:

Dear Tianzhu, HELP please! :?:


:? I don't understand \"Hence, 1 unit of bookmark ------- 12/6 ------- 2
1 unit of bookmarks ------- 8
There is an extra of 6 (8-2) because the bookmark costs 30 cents more than a sticker.
Number of bookmarks ------- 600/30 ------ 20
Therefore cost of 1 bookmark -------- 800/20 ------- 40 cents.\"

Hi

I am sorry for the error.

It should be read as 1 unit of stickers instead of bookmarks.

I'll revise the original post.

Please draw out the MD as it gives a clearer picture.

Best wishes

[tianzhu]

jarenchuatw:

2. A block of wood 40cm by 14cm by 8 cm was cut into smaller pieces which were 7cm by 6cm by 2cm each. What was the maximum number of pieces that it could be cut into?

Hi

One way of looking at this question.

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8001/7485835564_8dc81c8d0e_z.jpg\">

[mistychances]

Hi, saw this worked example in My Pals are Here.


Do not understand why the ''crooked'' path is being calculated as a straight path. Isn't a crooked one longer than a straigth one?

Will appreciate if someone can help to explain to me. Thank You

http://i47.tinypic.com/4jipk.jpg\">

[jarenchuatw]

Thanks BB, but could u explain how did u derive the below equation

SR:SC
9:12

How did u derive this equation?

Common distance question. Use ratio of speed and time to solve
TR : TC
12 : 9
SR : SC
9 : 12

3u -> 15
1u -> 5
speed of Rani -> 5 * 9 = 45 km/h
Distance = 45 * 12 = 540 km

Speed of chua -> 12 * 5 = 60km/h

[2632parent]

1) A car left Town A For Town B. At the same time a lorry left Town B for Town A. The average speed of the car was 90km/h while the speed of the lorry was 70km/h. The two vehicles passed each other at a point 36km away from the mid point between Town A and Town B. What was the distance between Town A and Town B?



2) Wendy had 80 more stamps than Mary but 50 more stamps than Jean. Wendy gives 1/2 of her stamps to Mary. Then Mary gives 1/5 of her stamps to Jean . If Jean has 62 more stamps than Wendy, how many stamps does Mary have in the end ?

:?:

[lizawa]

jarenchuatw:

Thanks BB, but could u explain how did u derive the below equation

SR:SC
9:12

How did u derive this equation?

Common distance question. Use ratio of speed and time to solve
TR : TC
12 : 9
SR : SC
9 : 12

3u -> 15
1u -> 5
speed of Rani -> 5 * 9 = 45 km/h
Distance = 45 * 12 = 540 km

Speed of chua -> 12 * 5 = 60km/h

Time is inversely proportional to speed, given that distance is common. So if ratio of speed is 12:9 then ratio of time will be 9:12

[MathIzzzFun]

2632parent:

1) A car left Town A For Town B. At the same time a lorry left Town B for Town A. The average speed of the car was 90km/h while the speed of the lorry was 70km/h. The two vehicles passed each other at a point 36km away from the mid point between Town A and Town B. What was the distance between Town A and Town B?



2) Wendy had 80 more stamps than Mary but 50 more stamps than Jean. Wendy gives 1/2 of her stamps to Mary. Then Mary gives 1/5 of her stamps to Jean . If Jean has 62 more stamps than Wendy, how many stamps does Mary have in the end ?

:?:

Hi

Q1.

http://i45.tinypic.com/raafk1.png\">

Q2.
Mary’s stamps --> 10 units
Wendy’s stamps --> 10 units + 80
Jean’s stamps --> 10 units + 30

After Wendy’s gave ½ her stamps to Mary,
½ Wendy’s stamps --> 5 units + 40
Mary’s stamps --> 15 units + 40 ---- ⅕ of Mary’s stamps --> 3 units + 8

After Mary gave ⅕ of her stamps to Jean,
Mary’s stamps --> 12 units + 32
Jean’s stamps --> 13 units + 38

In the end, Jean had 62 more stamps than Wendy,
13 units + 68 = 5 units + 40 + 68
1 unit --> 8

In the end, Mary’s stamps --> 12 x 8 + 32 = 128

cheers.

[corneyAmber]

Moderator's Note:


2636parent and mistychances, please do not start new threads for each question. Please read the forum rules before posting.


Forum rules

Gentle reminder before posting questions in the Academic Preparation & Support Forums: Please ensure you post your question in the correct thread. DO NOT start new threads. This gives moderators a lot of unnecessary work to move your threads to their correct places, and you may end up not knowing where your post went. Thank you.

[MathIzzzFun]

mistychances:

Hi, saw this worked example in My Pals are Here.


Do not understand why the ''crooked'' path is being calculated as a straight path. Isn't a crooked one longer than a straigth one?

Will appreciate if someone can help to explain to me. Thank You

http://i47.tinypic.com/4jipk.jpg\">

area of a parallelogram of height H, and base B has the same area as a rectangle of height H, and length B but the perimeter of same parallelogram is longer than that of the rectangle.

cheers.

[mistychances]

Sorry Moderator Will watch out the next time.


Thank you very much Math Izzz Fun Now I get the picture