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primary 5 | Maths
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How to draw model and find the answer
Date Posted: 3 years ago
Views: 309
You need to draw 5 units for the red pens at first in your model diagram.
20% of the red pens removed is basically 1 unit removed.
At the end, there are 4 units of red pens. There will also be 4 units of blue pens at the end since there are equal numbers of both colours.
So at the start, there are (4 units - 38) blue pens.
Recall that we had 5 units of red pens at first.
In total, there are (9 units - 38) pens, which is basically 250 pens.
So, we have
9 units - 38 = 250
9 units = 250 + 38 = 288 (this can be seen from your model)
1 unit = 288 / 9 = 32
From here, recall that there are (4 units - 38) blue pens at first.
4 units = 32 x 4 = 128
so number of blue pens at first
= 128 - 38
= 90
20% of the red pens removed is basically 1 unit removed.
At the end, there are 4 units of red pens. There will also be 4 units of blue pens at the end since there are equal numbers of both colours.
So at the start, there are (4 units - 38) blue pens.
Recall that we had 5 units of red pens at first.
In total, there are (9 units - 38) pens, which is basically 250 pens.
So, we have
9 units - 38 = 250
9 units = 250 + 38 = 288 (this can be seen from your model)
1 unit = 288 / 9 = 32
From here, recall that there are (4 units - 38) blue pens at first.
4 units = 32 x 4 = 128
so number of blue pens at first
= 128 - 38
= 90
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Date Posted:
3 years ago
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