Q&A - PSLE Math

[Recia Lim]

tianzhu:

Recia Lim:

Please help to solve this speed question. Thanks!

Question: Mrs Tan took 40 min to walk from her home to the market. On her return journey, she took an additional 8 min. her speed on the way back was 1km/h slower. What was the distance between her home and the market?

Hi

There are a few ways to do this question.

For this question, students may get their answers quickly using GC.

Another possibility is to use inverse proportion if students are familiar with it.

Given the same distance, speed is inversely proportional to time.

Higher speed needs less time.

Lower speed leads to more time.

Time ratio

40:48 ------- 5:6

Speed ratio ------- 6:5

1 unit ------ 1 km/h

5 units ------ 5 km/h

Distance between her home and the market ------- 5*48/60 ------- 4 km

Alternatively you may use the faster speed of 6 km/h

In this case, 6*40/60 ------ 4 km.

Best wishes

Thanks! How do we know when should we use this inverse proportion method?

[xiaotiao]

Can anyone help me to solve this problem, thanks!!!


The average weight of a group of boys is 50kg. If one more boy who weighs 76 kg joins the group, the average of weight will become 52kg. Find the number of boys in the group.

Hopefully a kind soul can do me a favour.

[Michaelia0816]

Tianzhu,

Pls help with this question. I do not understood the (a) part by http://2.bp.blogspot.com/_NGNaLTzN5_U/SrxBdiupjrI/AAAAAAAADz0/SzuIy0v5zX0/s1600-h/Maths0609SA2P2NYSpeedQ17A.JPG.

1) Ali saved some money in the form of $2, $5 and $10 notes. The value of the $2, $5 and $10 was in the ratio of 3:10 : 5. After taking out 2/3 of the $2 notes and 16 of the $5 notes to pay for a trip to China ,he had $2400 left. Find the value of the $10 notes that he had saved. ( Can I ask for the last step, I not sure if it is $1550 or $775)

[zanen]

tianzhu:

zanen:

mind helping with this question? thankyou. :)There is a big migic fruit tree in a garden. It bears fruits at a constant rate every day. Man will pick the fruits and sell. Animals will pluck and eat the fruits. 25 men can pick all the fruits in 15 days and 66 animals can eat all the fruits in 10 days. If 1 man can pick twice the number of fruits as 1 animal, find the number of days it take for 10 men to pick and 10 animals to eat all the fruits together?

Hi

Is this a PSLE type of question?

The answer to this question is 40 days.

How do you get the answer? mind sharing?

Best wishes

[Michaelia0816]

Recia Lim:

tianzhu:

[quote=\"Recia Lim\"]Please help to solve this speed question. Thanks!

Question: Mrs Tan took 40 min to walk from her home to the market. On her return journey, she took an additional 8 min. her speed on the way back was 1km/h slower. What was the distance between her home and the market?

Hi

There are a few ways to do this question.

For this question, students may get their answers quickly using GC.

Another possibility is to use inverse proportion if students are familiar with it.

Given the same distance, speed is inversely proportional to time.

Higher speed needs less time.

Lower speed leads to more time.

Time ratio

40:48 ------- 5:6

Speed ratio ------- 6:5

1 unit ------ 1 km/h

5 units ------ 5 km/h

Distance between her home and the market ------- 5*48/60 ------- 4 km

Alternatively you may use the faster speed of 6 km/h

In this case, 6*40/60 ------ 4 km.

Best wishes

Thanks! How do we know when should we use this inverse proportion method?[/quote]When the question asked you about the time and speed.

[Michaelia0816]

Michaelia0816:

Tianzhu,

Pls help with this question. I do not understood the (a) part by http://2.bp.blogspot.com/_NGNaLTzN5_U/SrxBdiupjrI/AAAAAAAADz0/SzuIy0v5zX0/s1600-h/Maths0609SA2P2NYSpeedQ17A.JPG.

1) Ali saved some money in the form of $2, $5 and $10 notes. The value of the $2, $5 and $10 was in the ratio of 3:10 : 5. After taking out 2/3 of the $2 notes and 16 of the $5 notes to pay for a trip to China ,he had $2400 left. Find the value of the $10 notes that he had saved. ( Can I ask for the last step, I not sure if it is $1550 or $775)

Pls help me!

[whitety]

susutoo:

please help:-)

There were 315 more adults than children at an exhibition at first. After 1/7 of the adults and 60% of the children left the exhibition, there were 462 more adults than children at the exhibition. How many people were at the exhibition at first.

My dd's method. Hope you understand the solution.

60/100=6/10=42/70
1/7=10/70

At first
A:C
70u+315:70u

1/7*(70u+315)=10u+45
42/70*70u=42u

Went away
A:C
10u+45:42u

In the end
A:C
60u+270:28u<---diff of 462
60u-28u=32u
462-270=192(32u)
1u=6
70u+70u+315=1155
Cheers :celebrate:

[Shimmer]

Hi, need help on this please. Thanks in adv.


Clare counted the number of 10cents, 20cents and 50cents in the bank. The no. Of 10cents was 17 more 50cents. After spending 60% of the 10cents, 25% of 20cents and 18 50cents, she had equal for all coins. The no. Of 50cents now formed 40% of not spent.

A) How many 10cents coin at first ?
B) How much spend in all ?

[tianzhu]

zanen:

How do you get the answer? mind sharing?

Hi

Good Morning.

Where is this question from?

Do you think it’s necessary to do such question for your PSLE preparation?

Best wishes

[tianzhu]

Michaelia0816:

Pls help me!

Hi ah girl

Good Morning.

You put up two posts in such a short span of time, 1059h and 1126h.

Don’t push me so hard leh.

We seek your understanding to give the volunteers reasonable time, and also many of the volunteers here are parents who may not be able to solve all your questions.

I am just an old man, the burdens of life are challenging enough.

I prefer my trip in KSP to be a relaxing cruise along River Safari. As such, I don’t like to rush through solutions.

When I clicked on the link, it was a Speed question.

Are you referring to the Speed question or Ali question?

Best wishes