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primary 6 | Maths
| Measurement
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Date Posted: 4 years ago
Views: 727
area of cardboard divided by area of one circle
method 1 (INCORRECT method) -
area of cardboard divided by area of one circle.
why incorrect? : there are spaces between circles that cannot be used
method 2 (INCORRECT method) -
area of cardboard divided by area of one square, with length of side of square equal to diameter of circle.
why incorrect? : this method will take care of the space between circles, but there may also be space at the edge of the cardboard that cannot be used
method 3 (CORRECT method)
no. of circles that can be placed along length of cardboard = 600 / 80 = 7.5
note that there is a portion that is 0.5 of the diameter of a circle, that cannot be used.
no. of circles that can be placed along width of cardboard = 400 / 80 = 5
greatest no. of circles that can be cut = 7 x 5 = 35
area of cardboard divided by area of one circle.
why incorrect? : there are spaces between circles that cannot be used
method 2 (INCORRECT method) -
area of cardboard divided by area of one square, with length of side of square equal to diameter of circle.
why incorrect? : this method will take care of the space between circles, but there may also be space at the edge of the cardboard that cannot be used
method 3 (CORRECT method)
no. of circles that can be placed along length of cardboard = 600 / 80 = 7.5
note that there is a portion that is 0.5 of the diameter of a circle, that cannot be used.
no. of circles that can be placed along width of cardboard = 400 / 80 = 5
greatest no. of circles that can be cut = 7 x 5 = 35
See 1 Answer
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Here you go.
The trick is: We want full circles, so for both the length and the breadth, they must fit in an entire circle.
Along 6m length, we can fit at most 7. If we try to squeeze in 8: 8 x 0.8m = 6.4m, more than 6m.
Along the 4m height, we can fit 5 of them nicely.
So in total, there can be 7x5 = 35 circles cut out.
The trick is: We want full circles, so for both the length and the breadth, they must fit in an entire circle.
Along 6m length, we can fit at most 7. If we try to squeeze in 8: 8 x 0.8m = 6.4m, more than 6m.
Along the 4m height, we can fit 5 of them nicely.
So in total, there can be 7x5 = 35 circles cut out.
Date Posted:
4 years ago
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