Q&A - PSLE Math

[tianzhu]

peggy:

Please help with this question. Thanks in advance.


Ben cycles from his home to the church every Sunday. If he were to cycle at 10km/h, he would reach the church at 3pm. If he were to cycle at 15km/h, he will reach there at 1pm. a) how far does Ben have to cycle from his home to the church? b) at what average speed must he cycle if he wants to reach the church at 2pm?

Hi

There are a few ways to solve this question.

One way is to use inverse proportion.

Speed is inversely proportional to time (distance remains constant).When speed is higher, time taken is shorter.

Speed ----- 2:3 (10:15)
Time ------- 3:2

1 unit ------ 2h (1pm and 3pm)

2 units ------ 4h
Distance ------- 15*4 ------- 60km

Alternatively
3 units ------ 6h
Distance ------ 10*6 ------ 60km

If he wants to reach the church@2pm

Time taken ------5h

60/5 ------ 12km/h

Best wishes

[peggy]

Tianzhu,


Thank you so much for your quick reply.

All the best!

Peggy

[JGMum]

jarenchuatw:

Yup, 100% correct. But had problem explaining to my son, he could not comprehend why I need to add 8 secs and not 12 seconds. Whew, it took a while before he got the picture. Tks!

That's great, thanks for the feedback!

[Winx5015]

Hi tianzhu,


thanks for your solution.

Good nite

[Michaelia0816]

Do try to find the answer as it was a great example of Math PSLE. I would tell the correct again later in a while. DO post your answer!

The Lim family were great mathemacticians. When a reporter wanted to interview them, she asked for everyone's ages! The family replied to her, \" Our family of 2 adults and 3 children are a total of 100 years old together. The sum of father and his son ages was 51 years old. The mother ages was 3 years younger than the father while the twins daughter were each 5 years younger than her brother.\" So what were their ages ? (Hint: Draw model)
:xedfingers:

[tianzhu]

Michaelia0816:

Do try to find the answer as it was a great example of Math PSLE. I would tell the correct again later in a while. DO post your answer!

The Lim family were great mathemacticians. When a reporter wanted to interview them, she asked for everyone's ages! The family replied to her, \" Our family of 2 adults and 3 children are a total of 100 years old together. The sum of father and his son ages was 51 years old. The mother ages was 3 years younger than the father while the twins daughter were each 5 years younger than her brother.\" So what were their ages ? (Hint: Draw model)
:xedfingers:

Hi

If I remember correctly, a similar question has been discussed before.

Daughter ------ 6
Son ------ 11
Father ------- 40
Mother ------ 37

Best wishes

[tianzhu]

Hi


It’s time of the year again when the topic on “Speed” will be covered in the school syllabus.

If you refer to the PSLE Maths thread, the term inversely proportional or inverse proportion has been mentioned regularly when dealing with Speed questions.

Inverse proportion is covered in Secondary Two syllabus. However, I believe many schools are introducing such concept to selected classes.

It is worthwhile to spend a bit of time understanding this concept as it’ll give students a different approach.

It’s not too difficult to grasp it. When travelling a certain distance, if you travel at a faster speed, you will take a shorter time to reach your destination. Speed increases, Time decreases. Speed decreases, Time increases.

You may apply the inverse proportion concept on these questions.

Ben cycles from his home to the church every Sunday. If he were to cycle at 10km/h, he would reach the church at 3pm. If he were to cycle at 15km/h, he will reach there at 1pm. a) how far does Ben have to cycle from his home to the church? b) at what average speed must he cycle if he wants to reach the church at 2pm?

Ann is driving to a destination. If she travels at 80km/h, she would be 20min late. If she travels at 60km/h, she would be 45 min late. How long will journey take if she travels at 90km/h.

Best wishes.

http://farm8.staticflickr.com/7140/7010307049_02abdcfae5_z.jpg\">

[YumYum]

Hi, need help with this Qn:


Rachel and Nicole set off the park and travelled towards their school at the same time. At 10 am, Rachel was 600m ahead of Nicole.

Nicole caught up with Rachel at 10.30am.

Given that rachel travelled at an average speed of 60 m/min , find nicole’s average speed.

Thanks

[peggy]

Please help with some speed questions here.


1. At 9.30am, Train One which was 200m long, pulled out of Station X and traveled towards Station Y at a uniform speed of 80km/h. Half an hour later, Train Two which was 150m long, left Town Y and traveled towards Town X at a uniform speed of 90 km/h.
A) How far Train One traveled when Train Two left Station Y?
B) The two trains met each other of the tunnel. Calculate the length of the tunnel.

2.Alvin started traveling from Town P towards Town Q at 7am. After traveling for some time, he passed Simon who was traveling at an average speed of 80km/h in the opposite direction. After traveling for another 2 hours, Alvin reached town Q while Simon was still 40 km away from Town P.
A) if Alvin reached town Q at 1 pm, what was his average speed?
B) if Simon started his journey from town Q, at what time did he leave Town Q ?

3. A van started from town A and traveled towards town B. At noon when the van was 80km from town A, a truck which was 20km/h faster than the van started from town B and traveled towards town A. When the truck reached town A at 6pm, the van had traveled only 90% of its journey. Find the speed of the lorry in km/h.

Thank you.

[Winx5015]

Hi need help for the following questions.


(1). Jane has 20% more stamps than Eunice. Eunice has 20% less stamps than Mary. If Jane has 48 fewer stamps than Mary, how many stamps do the three girls have altogether?

(2). There were 30% more cars registered in October than in September. In November, the number of cars registered increased by 20% compared to October. If a total of 19300 cars were registered in the three months, how many cars were registered in September?

Thanks