Tutor MathsGuru: Ask me for your burning Maths questions!

[mathsguru]

Seekinghelp:

Ty for yr explanation but I still dun get it. Is it possible u draw out the model and show me? Btw, yr ans is correct. So sry still need to ask u 1 more ques.


Tank A had 345 litres of water more than Tank B. Tank B had 500 litres of water less than Tank C. How much more water was there in Tank C than in Tank A? This ques is extracted fr 1 of the school exam ques but I duno how to explain it to my nephew, is it possible u show me with model drawing too?

Hi Seekinghelp,

Sorry for the delayed response. Just saw your posting...

Anyway, here's my detailed working for your 2 questions, similar to what the other 2 helpful KiasuParents member provided.

http://www.postimage.org/image.php?v=Pq1Jkbsr

http://www.postimage.org/image.php?v=Pq1JkdXA

Hope this clears your doubts!

Thanks and regards,
MathsGuru

[Seekinghelp]

Ty Muffins, Tutormum and Mathsguru for ans! Now i understand how to do it.


Next ques: The sum of two numbers is 15 but the difference is 7. Find the bigger number.

It seems like I'm the only one who keep asking ques :lol: Paisey.
I know the ans is 11 but i duno hw to guide him thru explanation.

[Muffins]

Seekinghelp:

Ty Muffins, Tutormum and Mathsguru for ans! Now i understand how to do it.


Next ques: The sum of two numbers is 15 but the difference is 7. Find the bigger number.

It seems like I'm the only one who keep asking ques :lol: Paisey.
I know the ans is 11 but i duno hw to guide him thru explanation.

Hi Seekinghelp, the problem can be solved in two ways. Both, easy to understand and explain. I'll give both of them.

The first way
15 - 7 = 8
8/2 = 4
15 - 4 = 11

The second way is longer but easier to explain...
Bigger number + smaller number = 15
Bigger number - smaller number = 7

So, bigger number + smaller number + bigger number - smaller number = 15 + 7 = 22

Which is the same as bigger number + bigger number = 22

So 1 of the bigger numbers is 22/2 = 11

Hope I helped!

[mathsguru]

Seekinghelp:

Next ques: The sum of two numbers is 15 but the difference is 7. Find the bigger number.

Hi Seekinghelp,

You're most welcome! And please don't say that of yourself...We're all here to help...

I've drawn out the models for this question. It should be easier for you to explain as there's something to visualise.

http://www.postimage.org/image.php?v=aV1rG4l9

Cheers,
MathsGuru

[suiyuan]

Hi mathsguru


Please share your solutions for these speed questions.

1) Terry walks to school at an average speed of 4km/h every day. One day, after walking a distance of 1km, he realised that his watch was slow. So, he ran at a constant speed and managed to reach the school just on time. Later, he calculated that if he had run at this speed right from the start of the journey, he would have reached school 5 minutes earlier. What was his running speed?

2) Amy took 3 hours to travel from Town P to Town Q. Pansy took 2 hours to travel from Town Q to Town P. Both of them started travelling at 9am. At what time did they pass each other?

3) Courier A takes 10 hours to deliver a parcel from Town X to Town Y. Courier B takes 12 hours to deliver the parcel along the same route. If the speed of Courier A is 9km/h faster than that of Courier B, find the speed of Courier A.

4) Lily is meeting a friend at a certain time. If she drives at 80 km/h, she will be 1/3 hour late. If she drives at 60 km/h, she will be 3/4 hour late. How long will the journey take if she drives at 90 km/h?

5) Simon cycled at an average speed of 10km/h from his house to the park. On reaching the park, he cycled back home along the same route at an average speed of 8km/h. He took 1h 12 mins for the entire journey. How long did he take to cycle from the park back to his home?

Thank you.

[kiasimom]

Hi Mathsguru,

Thank you for your offer to help.

Will surely ask you for help in future.

Thanks in advance :udaman:

[Seekinghelp]

It's great to have pple like u guys to help us selflessly. Tysm

[mathsguru]

suiyuan:

1) Terry walks to school at an average speed of 4km/h every day. One day, after walking a distance of 1km, he realised that his watch was slow. So, he ran at a constant speed and managed to reach the school just on time. Later, he calculated that if he had run at this speed right from the start of the journey, he would have reached school 5 minutes earlier. What was his running speed?


2) Amy took 3 hours to travel from Town P to Town Q. Pansy took 2 hours to travel from Town Q to Town P. Both of them started travelling at 9am. At what time did they pass each other?

3) Courier A takes 10 hours to deliver a parcel from Town X to Town Y. Courier B takes 12 hours to deliver the parcel along the same route. If the speed of Courier A is 9km/h faster than that of Courier B, find the speed of Courier A.

4) Lily is meeting a friend at a certain time. If she drives at 80 km/h, she will be 1/3 hour late. If she drives at 60 km/h, she will be 3/4 hour late. How long will the journey take if she drives at 90 km/h?

5) Simon cycled at an average speed of 10km/h from his house to the park. On reaching the park, he cycled back home along the same route at an average speed of 8km/h. He took 1h 12 mins for the entire journey. How long did he take to cycle from the park back to his home?

Dear Suiyuan,

Here are my detailed solutions. A useful tip to note for speed questions is that speed and time are inversely proportional. So, many a time, for questions without much details, we can solve them by comparing their ratio for speed and inversing it to get ratio for time, and vice-versa.

Hope my workings and diagrams are clear enough!

Regards,
MathsGuru

http://www.postimage.org/image.php?v=Pq1NC_GA

http://www.postimage.org/image.php?v=Pq1ND2aJ

http://www.postimage.org/image.php?v=Pq1NCTc9

http://www.postimage.org/image.php?v=Pq1NCVHi

http://www.postimage.org/image.php?v=Pq1NCYbr

[KSP]

tamarind:

Dear all who replied to my question,

My friend said it is from an assessment book. The answer is not 175.

I just wanted to confirm that there is something wrong with this question. The publisher need to correct this mistake.

Either the question or answer is wrong.

[KSP]

I feel that to help our kids do well in Maths, we have to let them learn how to solve these mind twisting questions. Some of the PSLE Maths questions even we as parents can’t solve them. I feel that schools are not doing enough in this area.


While we can share our workings and solutions here, but when come to explaining to our kids they may not understand or take a while to absorb. I’m not sure this is the right approach. But I still think there should be a proper method in teaching our kids to solve model questions.

Is there anyone here watch the Friday night 10.30pm Ch8 show about the P6 student saying how tough the PSLE Maths paper.

The thing that interest me was when they asked the HCI and NYGH students to solve the "Ken Jim chocolate sweet" question, one of the NYGH said she already know how to answer this type of question when she was P5 and she learnt it at an enrichment class. So I really wonder which enrichment class teaches this. Is it Learning Lab, Dr Peh or etc… can do the job?