This Q testd on the understanding of "average", which means something bigger gives up a portion of itself to something smaller, so that they have the same size in the end.

Both the cupboard and sofa are heavier than the TVs. The extra weight is equals to (41kg-36kg)+(39kg-36kg)＝8kg.

After this 8 kg is shared equally among TVs, the anerage mass increased by 2kg. In other words, each TV "recieved" 2kg. So number of TVs ＝8/2＝4.

used the mass of the cupboard and sofa to minus 36 is because 36kg is the final average mass, which includes the cupboard and sofa. So the extra mass the cupboard and sofa has is "given away" to the TVs equally to increase the average mass.

Guess and check or assuming method

With table

I think it's g n c too.

Start w 30 each and then adjust the qty accordingly.

For guess and check, always start half (=number). Then you choose to increase or decrease according.

start with 60 3s.. so you get 180 wheels.. now check how many wheels do you need more to match the desired number of wheels.. that's 33.. so you have 33 4s and 27 3s :) hope i helped :) sorry i'm lazy to elaborate try to understand it :)

Also: assume all is for the the toy with less wheels. 60x3=180. Means 33 wheels missing. In this case, you would need 33 toy cars and 27 tricycles. Hope that makes sense

Guess and Check will take too long. Agree with Joshua's method.

60 X 3= 180 213-180 = 33 cars 60-33= 27 tricycles

At P3 level, they are taught to use Guess & Check though.

Huixian is right, have to follow method taught in school.

Thank you all. Appreciate ur help in solving this qn 😊

There are another method. If question ask to find tricycle. Then we must use : total toy 60 x 4 (use opposite toy) = 240 And then use total 240 -213 =27 x 1 wheel differ. {differ 4 wheel vs 3 wheel}

U can try this question.

Huixian and Thomas, is it necessary to follow the method taught in school? Are students given room to be creative and try altenative methods, esp when the alternative method used (like what Joshua did) is logical and makes sense?

It is not a must, but I believe the methods taught are based on what a typical kid of that age is capable of understanding. Some may not be able to understand using the supposition method at this age. It is however not wrong to use it, unless they specifically say to use the G&C method. My girl is at P3 now, and she has not been taught the supposition method for solving such problems. I believe supposition is taught at the upper pri level? My personal preference to solving this would be using algebra, but I think that might be a little tough to understand at P3 level.

As The school teacher is given this answer to P3 students. Tat why I need to do this to explain to my P3 girl. Or use the guess & check method.

My gal is P3 n taught to use this method. Maybe alternative method to be used as counter Checkling?

in both cases, the only difference is that 5 chairs is bought in the first case, while an oven is bought in the second case. In the second case, if the oven would to be cheaper by $38, Amy will have just enough to buy the oven. If so, the oven will also cost $254-$38＝$216 more expensive than a chair only. Since 5 chairs can be bought with this amount of money too, we can see that the difference between the (cheaper) oven and a chair, which is $216, is 4 times the cost of a chair. So one chair costs $216/4＝$54. Hence, Amy will be left with $54x5＝$270 if she only bought the table.

Perhaps this model will help a little ....

Thanks for the help😄

For ratio question, good to ask what remains the same. So in this case, the number of students in group 1 and group 2 are the same. Looking at total units in group 1 and group 2, if we can make the total number of units the same, then we can compare between the groups.

So we need to multiply 2: 1 by 3 to get 6:3 with a total units of 9. Now can compare with 7:2.

Thanks! Mental block

Working too hard, LiLi Goh.