Tutor MathsGuru: Ask me for your burning Maths questions!

[Vanilla Cake]

Dharma:

YLH88:

Hi Vanilla Cake, Dharma,

Thank you!!

Vanilla Cake,
for this question, why do you take 21-(-35) ? Can I just take 21+35 ? It will be easier to explain to my DS, don't think they are taught on -- = + yet or I could be wrong. My DS is in P6 this year.[quote]2) Every day, Samir reads 7 pages of a story book and Dion reads 2 pages more than Samir.Dion starts to read only 5 days after Samir has started. After some time, Dion has read 21 pages more than Samir.How many pages has Samir read by then ?

[quote]Number of pages read by Samir on a daily basis = 7
Number of pages read by Dion on a daily basis = 7+2 = 9
Difference = 9-7= 2 pages

After 5 days, Samir has read 7x5 = 35 pages (Dion is behind by 35 pages)
Number of pages for Dion to catch up = 21-(-35)=21+35=56

56 divided by the difference = 56/2 = 28 days
28x7=196
By then, Samir has read 196 pages.

Thank you!![/quote]Hi YLH88,
The total no. of pages read by Samer = 196 + 35 =231[/quote]Hi YLH88,
Thanks for your highlight. You are right and you can take 21+35 which is easier to explain at P6 level. As highlighted by Dharma, pls add the number of pages read by Samir for the first 5 days (5x7=35) and add on the pages read for the next 28 days(28x7=196). So, total pages read by Samir should be 35+196=231 by then (5+28=33 days).

Thanks to Dharma for correcting my workings.

[adhdadhd]

Having read recent posted solutions, which were mostly solved by using algebra, I tried solving some of them using models, but it seems impossible to, as they involved multiplications of units.


How do we then teach our kid, to consider giving up using model?

My DS is Pri 5 now, and I can’t explain to him using algebra.

[zenztormz]

adhdadhd:

Having read recent posted solutions, which were mostly solved by using algebra, I tried solving some of them using models, but it seems impossible to, as they involved multiplications of units.


How do we then teach our kid, to consider giving up using model?

My DS is Pri 5 now, and I can't explain to him using algebra.

MOE has released a publication on MODELS ... it is available in popular bookshop, you can read on that before teaching your kid...but it is kinda expensive..

[CoffeeCat]

adhdadhd:

Having read recent posted solutions, which were mostly solved by using algebra, I tried solving some of them using models, but it seems impossible to, as they involved multiplications of units.


How do we then teach our kid, to consider giving up using model?

My DS is Pri 5 now, and I can't explain to him using algebra.

my opinion is that models used to be powerful in my generation but very limited now that there are so many variety of challenging problems sums involving fractions and ratio. A pure model method is only going to make things look untidy when you have to divide your model into 20 equal parts. It is possible to avoid algebra for most of the questions by using branching (fraction) or ratio method.
If I am not wrong that book is expensive but doesn't help much with the challenging ones, my opinion, might not be true.

[KSP]

CoffeeCat:

adhdadhd:

Having read recent posted solutions, which were mostly solved by using algebra, I tried solving some of them using models, but it seems impossible to, as they involved multiplications of units.


How do we then teach our kid, to consider giving up using model?

My DS is Pri 5 now, and I can't explain to him using algebra.

my opinion is that models used to be powerful in my generation but very limited now that there are so many variety of challenging problems sums involving fractions and ratio. A pure model method is only going to make things look untidy when you have to divide your model into 20 equal parts. It is possible to avoid algebra for most of the questions by using branching (fraction) or ratio method.
If I am not wrong that book is expensive but doesn't help much with the challenging ones, my opinion, might not be true.

Have you tried this book? http://www.kiasuparents.com/kiasu/files/file/maths_heuristics_books_utm.jpg\">

I think is very useful.

You can find out more from http://www.mathsheuristics.com/

[adhdadhd]

Hi Zenstorm, Coffecat and KSP.

Thank you for speedy response,
I will look at your suggestions.

[Almighty]

Hi,


Please help me solve this problem

Gin left Town P at 6.45 a.m. and travelled at 80Km/h along a highway. Two hours later, Mr Brown left Town P and travelled at 100Km/h along the same highway. At what time did he overtake Gin?

Ans : 4.45Pm

[Sun_2010]

Almighty:

Hi,


Please help me solve this problem

Gin left Town P at 6.45 a.m. and travelled at 80Km/h along a highway. Two hours later, Mr Brown left Town P and travelled at 100Km/h along the same highway. At what time did he overtake Gin?

Ans : 4.45Pm

When Mr. Brown starts, distance between Gin and him = 2 hr x 80kmph
= 160km
Difference in between Mr. Brown and Gin's speed = 100kmph - 80kmph
= 20kmph

So time taken for Mr.Brown to catch up with Gin = 160km / 20kmph
= 8hrs

which would 2hrs+8hrs after 6:45am = 4:45pm

[Dharma]

Almighty:

Hi,


Please help me solve this problem

Gin left Town P at 6.45 a.m. and travelled at 80Km/h along a highway. Two hours later, Mr Brown left Town P and travelled at 100Km/h along the same highway. At what time did he overtake Gin?

Ans : 4.45Pm

Both Gin and Brown travelled the same distance from
Town P when Brown overtook Gin. So, when distance is constant, speed is inversely proportional to the time taken.
Speed ratio => Gin : Brown = 4:5
Time ratio => Gin : Brown = 5:4

5u - 4u = 1u = 2 hrs
4u = 8hrs
Brown overtook Gin 8 hrs after he left Town B.

8 hrs after 8.45am => 4.45pm

[YLH88]

Hi Vanilla Cake, Dharma,


Thank you for the explanation!!

Have a good day