Q&A - PSLE Math

[Vanilla Cake]

sexymama:

(1) On the way to SV town, Hans overtook Chris when they were 120 km from SV. When Hans reached SV, Chris still had 20 km to travel. Chris finally arrived at SV 15 minutes later.

(a) Find Chris' average speed
(b) Find Hans' average speed

15 min-> 20 km
1 h -> 80 km

(a)Chris average speed was 80 km/h.

Required time for Chris to reach SV town = 120÷80 = 1½h
Required time for Hans to reach SV town = (1½-¼)h = 1¼h
120km÷1¼h = 96 km/h

(b) Han's average speed was 96 km/h

[Vanilla Cake]

sexymama:

(2) Town A and Town B were 1080 km apart. At 7 a.m. Mr Tan started driving from Town A to Town B. At the same time, Mr Hamid started driving from Town B to Town A at a speed 10 km/h faster than Mr Tan's. At 12 noon, they were 180 km apart. Find Mr Hamid's speed if they were travelling at constant speeds.

Assume that constant speed of Mr Tan be u km/h
Constant speed of Mr Hamid = (u+10)km/h
From 7 am to 12 noon, time lapsed = 5 hours
Distance travelled by Mr Tan = 5u
Distance travelled by Mr Hamid = 5(u+10) = 5u+50
Distance apart between them was 180 km and total distance between Town A and Town B was 1080 km,

5u+180+5u+50=1080
10u+230=1080
10u = 850
u = 85

85+10 = 95
Constant speed of Mr Hamid = 95 km/h

Hope this helps.

[liketoeat]

Hi, I need help with these questions…


1) A driver and a motorcyclist both started at the same time to travel to town B, 540 km from town A. The car was travelling at an average speed 50 km/h faster than the motorcycle for the first 1.5 h. After that, the motorcyclist doubled his speed to catch up with the car. However, he arrived at town B slightly more than 6 minutes later than the car. If the motocyclist were to arrive at the same time as the driver, at what speed should he increase to instead? (Ans: 145 km/h)

2) The distance around the perimeter of a reservoir is 5.52 km. Rick and Reuben started walking from the same point but in the opposite direction round the reservoir. Rick’s speed was 25 m/min and he rested for 5 minutes after every 35 minutes. Reuben’s speed was 35 m/min and he rested for 15 minutes after every 45 minutes. How long did it take both of them to meet again? (Ans: 104 min 55 s)

Thank you.

[James Ang]

atutor2001:

Joy:

Hi All,


Good morning.

Below is a math question from my dd, p5 sa1 exam.I also noticed similar question came out in another school for p6 sa1 this year.

Just wonder, anyone has seen similar question before?If yes, kindly advice where is the source?

Mdm Lek had 57 apples and oranges altogether.There were 3 fewer oranges than apples.She gave away half as many oranges as apples to her neighbours.vShe was left with twice as many oranges as apples.How many apples did she give away?

thank you.Regards
Joy

Hi Joy

This type of question can be found in many exam papers. The characteristic of such question is that the examiner has added one more working step by giving the actual number of apples and oranges \"indirectly\" - i.e. from the total of 57 and the difference of 3, students can find the actual no. of apples and oranges.

This additional working step can be incorporated into all kinds of questions involving 2 quantities but will usually leave students totally confused. I remembered telling my kids to specially look out for information given in this way (i.e. total with difference).

someone asked me this question on facebook, I suppose this question is not difficult and P5 students can usually solve by drawing a model (which they are taught in school how to solve).

57 apples and oranges
57-3 = 54
54/2 = 27
she has 27 oranges and 30 apples at first.

after
orange [][]
apples []

before
orange [][]()= 27
apples []()() = 30
total = [][][]()()() = 57
therefore []()= 57/3 =19
() = 30- 19 = 11
()() = 11x2 = 22 apples gave away

[sexymama]

Thank you vanilla cake

for the solution.... :lol:

[ruyu]

sexymama:

(2) Town A and Town B were 1080 km apart.
At 7 a.m. Mr Tan started driving from Town A to Town B.
At the same time, Mr Hamid started driving from Town B
to Town A at a speed 10 km/h faster than Mr Tan's.
At 12 noon, they were 180 km apart.
Find Mr Hamid's speed if they were travelling at constant speeds.

easier methord:

1080-180=900

5 hours
7 a.m -------------- 12 noon is

10 x 5= 50(since Mr Hamid is travelling 10km/h faster he travelled 50km more than Mr Tan)

900-50=850(now the distance they travelled is the same)

850/2=425(distance Mr Tan travelled in 5 hours)

425+50=475(distance Mr Hamid travelled in 5 hours)

475/5=95

95km/h

[Vanilla Cake]

liketoeat:

2) The distance around the perimeter of a reservoir is 5.52 km. Rick and Reuben started walking from the same point but in the opposite direction round the reservoir. Rick's speed was 25 m/min and he rested for 5 minutes after every 35 minutes. Reuben's speed was 35 m/min and he rested for 15 minutes after every 45 minutes. How long did it take both of them to meet again? (Ans: 104 min 55 s)

This Q2 was taken from:
Problem-Solving Made Easy!
An Innovative Mathematics Assessment Guide Series
Using '4-Stage Thinking Guide'
Highly Recommended Primary 6 MOE Syllabus
Written by Tan Li Ling and Teo Chee Kian
Published by ACE Publications
Booklet - Rate & Speed
Q27 on page 32 and answer on separate answer booklet - page 27
(Due to copyright issue, answer from this assessment book will not be written)

Pls refer to http://psle2010a.blogspot.com/2010/06/speed-p6_09.html.

Hi Chief/Admin/Mods,
Is it possible to have a sticky thread in KSP forum to remind members who post questions for others to solve to have some sort of proper etiquette?
As a form of basic courtesy and appreciation for the time and effort by the online problem solving fraternity, it would be good if the thread starters for the questions can:

(1) Quote the source of their question/s.Schools/tuition centres/assessment books or others?
(2) Level for their questions - P5,P6 or others?
(3) Whether thread starters are parents or students? If they are parents then no need to have long-winded Maths explanations.

No offence to anyone as it is just my 2 cents thought.

[liketoeat]

Thank you Vanilla Cake.

[Vanilla Cake]

liketoeat:

1) A driver and a motorcyclist both started at the same time to travel to town B, 540 km from town A. The car was travelling at an average speed 50 km/h faster than the motorcycle for the first 1.5 h. After that, the motorcyclist doubled his speed to catch up with the car. However, he arrived at town B slightly more than 6 minutes later than the car. If the motocyclist were to arrive at the same time as the driver, at what speed should he increase to instead? (Ans: 145 km/h)

Pls refer to http://psle2010a.blogspot.com/2010/06/speed-p6_10.html.

[Vanilla Cake]

Vanilla Cake:

Hi Chief/Admin/Mods,

Is it possible to have a sticky thread in KSP forum to remind members who post questions for others to solve to have some sort of proper etiquette?
As a form of basic courtesy and appreciation for the time and effort by the online problem solving fraternity, it would be good if the thread starters for the questions can:

(1) Quote the source of their question/s.Schools/tuition centres/assessment books or others?
(2) Level for their questions - P5,P6 or others?
(3) Whether thread starters are parents or students? If they are parents then no need to have long-winded Maths explanations.

No offence to anyone as it is just my 2 cents thought.

Hi Chief/Admin/Mods,
Just to add some more points:

4. If it is possible for the thread starter of the question, pls kindly include your correct answers (if you have them).This will help the potential online helper to serve as a check and reduce the amount of \"wrong teachings\" if the online helper delivers the wrong method/answer.

5. Pls post the right question at the right level in the right thread.Do not post secondary Maths questions in a PSLE Maths thread and expect answers.

6. It is VERY important to state the level that your questions belong to.This will ensure that online helpers use the right explanations within the scope of your syllabus and they do not resort to complex calculations/theorem that can solve your questions but not acceptable by your school teachers.

7. Do not expect instant answers as online helpers do not operate round the clock and watch KSP forum all the time.Pls kindly allow some time before your questions are answered and do not expect to be totally spoonfed.

8. Online helps are not godly and cannot guarantee that all their answers are perfect and 100% correct.Pls do not compare their methods if you feel that your own methods are more efficient and easier. These online helpers are just volunteering their services to help those in need and do not expect anything in return.

9. Pls help to post the question in its original state and do paraphrase the question.Paraphrasing does changes the meaning of the question and may lead online helpers to the wrong tracks. So, pls type out your question in the exact way and manner in which it was presented to you. Pls check the question again to reduce typo errors.

10. If possible, please post the complete questions including the sub-questions related to the question that are trying to solve.It may save you time to post just part of a question. But this leaves out certain critical information about the question that may mislead online helpers or prevent them of adopting a faster/more efficient way to provide the solution.

Last of all, if the questions are from tuition centres, you may prefer to ask your tutors.If the questions are from assessment books, then refer to them and no need to seek online help.Most important of all is to state the level that your question comes from.(See point 6)

Thanks.