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Primary 4 | Maths
2 Answers Below
Anyone can contribute an answer, even non-tutors.
Please help. Thanks
Date Posted: 4 years ago
Views: 426
nos.
total=47
tri: 1u
bi: 47-1u
wheels
total=115
tri: 3u
bi: 94-2u
94 + 1u = 115
1u = 21
21 tri
.
.
.
total=47
tri: 1u
bi: 47-1u
wheels
total=115
tri: 3u
bi: 94-2u
94 + 1u = 115
1u = 21
21 tri
.
.
.
Sorry, I don understand. Are you able to explain further?
Try doing "guess and check" method
Is such sum meant to not let students score? Haha..
Tricycle has 3 wheels.
Bicycle has 2 wheels.
Assume all 47 are bicycles.
Number of wheels = 2 x 47
= 94
The number of wheels is too few since there are 115 in total.
We need to replace some bicycles with tricycles.
For every 1 bicycle that we replace with a tricycle, we are adding 1 more wheel to the total since tricycle has 3 wheels but a bicycle only has 2.
(3 - 2 = 1)
Number of wheels we must increase by
= 115 - 94
= 21
Number of bicycles that we need to replace
= 21 ÷ 1
= 21
This means that there were actually 21 tricycles in the first place.
Bicycle has 2 wheels.
Assume all 47 are bicycles.
Number of wheels = 2 x 47
= 94
The number of wheels is too few since there are 115 in total.
We need to replace some bicycles with tricycles.
For every 1 bicycle that we replace with a tricycle, we are adding 1 more wheel to the total since tricycle has 3 wheels but a bicycle only has 2.
(3 - 2 = 1)
Number of wheels we must increase by
= 115 - 94
= 21
Number of bicycles that we need to replace
= 21 ÷ 1
= 21
This means that there were actually 21 tricycles in the first place.
Assumption is that no extra wheels are mounted at the back of the cycle as a spare wheel (like how some cars attach a spare wheel at the back).
Needless to say, those don't count. Besides, this is tagged P4 so the number of wheels are taken as it is.
We do not throw in any other factors since that would result in multiple possibilities. (Training wheels, spare tyres, etc)
See 2 Answers
done
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Hope this helps!
Date Posted:
4 years ago
If we use 47 X 3, the total number of wheels will exceed 115.
Not correct. It should be 21 ÷ 1 = 21 tricycles.
We have to replace some bicycles with tricycles such that the number of cycles remains at 47 but the number of wheels increases.
For each bicycle that is replaced, there is an increase of 1 wheel
(Taking a bicycle away means 2 wheels are subtracted, but adding a tricycle in its place means adding 3 wheels. There is a net/overall increase of 1 wheel)
We have to replace some bicycles with tricycles such that the number of cycles remains at 47 but the number of wheels increases.
For each bicycle that is replaced, there is an increase of 1 wheel
(Taking a bicycle away means 2 wheels are subtracted, but adding a tricycle in its place means adding 3 wheels. There is a net/overall increase of 1 wheel)
Ahh right, sorry for the error and confusion.
Thanks
done
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Try to read and slowly understand.
Date Posted:
4 years ago
Not a good idea to use algebraic approach. Bear in mind that the question is posted as a Primary 4 question.
What would your answer be then?
You will need to use the assumption method (practically guess and check) at the Primary 4 level. Using algebraic expressions like x and y is more appropriate for a Secondary 2 student.
I know you have tried to explain the equation in the simplest of way to the student, but then again. the level gap is still too big.
Perhaps if you used "units" and "parts" instead of x and y, they might be able to absorb the terms better. But then again, if I recall, "units" and "parts" are used together only at the Primary 5 or at the Primary 6 level.
----------------------------------------------
A bicycle has 2 wheels.
A tricycle has 3 wheels.
Assume that all 47 cycles are bicycles.
Number of wheels for 47 bicycles
= 47 x 2
= 94
But there are 115 wheels. So, there cannot be 47 bicycles.
Replacing a bicycle with a tricycle keeps the number of cycles the same, but increases the number of wheels by 1.
To get 115 wheels, we need to add 21 wheels altogether. This means a total of 21 bicycles have to be swapped to tricycles, leaving behind 26 bicycles.
Therefore, there are 21 tricycles and 26 bicycles.
Check:
Number of wheels from tricycles
= 21 x 3
= 63
Number of wheels from bicycles
= 26 x 2
= 52
Total number of bicycles
= 63 + 52
= 115
The students at Primary 4 use the assumption method to solve such questions, often presented in a table format.
I know you have tried to explain the equation in the simplest of way to the student, but then again. the level gap is still too big.
Perhaps if you used "units" and "parts" instead of x and y, they might be able to absorb the terms better. But then again, if I recall, "units" and "parts" are used together only at the Primary 5 or at the Primary 6 level.
----------------------------------------------
A bicycle has 2 wheels.
A tricycle has 3 wheels.
Assume that all 47 cycles are bicycles.
Number of wheels for 47 bicycles
= 47 x 2
= 94
But there are 115 wheels. So, there cannot be 47 bicycles.
Replacing a bicycle with a tricycle keeps the number of cycles the same, but increases the number of wheels by 1.
To get 115 wheels, we need to add 21 wheels altogether. This means a total of 21 bicycles have to be swapped to tricycles, leaving behind 26 bicycles.
Therefore, there are 21 tricycles and 26 bicycles.
Check:
Number of wheels from tricycles
= 21 x 3
= 63
Number of wheels from bicycles
= 26 x 2
= 52
Total number of bicycles
= 63 + 52
= 115
The students at Primary 4 use the assumption method to solve such questions, often presented in a table format.
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