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primary 5 | Maths
| Percentage
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Date Posted: 4 years ago
Views: 772
Pencil: $1
Eraser: $0.60
Bought 8 more erasers than pencils
Spent $4 more on pencils than erasers
How many pencils?
A relatively easy way to do this is to make the number of pencils and erasers the same.
Suppose Joyce had bought 8 more pencils, so that the number of erasers and pencils bought be the same. This would mean that Joyce would spend $8 more than she would do for pencils in the original story, and as such, she would pay $12 more for pencils than erasers in this case (where she bought 8 more pencils than in the story).
Now, every one pencil cost $0.40 more than every one eraser. This is one group.
Because she spent $12 more on pencils than erasers, number of groups would be $12/$0.40 = 1200 cents / 40 cents = 30.
So in this case, she would have bought 30 pencils and 30 erasers.
In the original story, 8 of the pencils were not actually bought, so number of pencils bought
= 30 - 8
= 22
Eraser: $0.60
Bought 8 more erasers than pencils
Spent $4 more on pencils than erasers
How many pencils?
A relatively easy way to do this is to make the number of pencils and erasers the same.
Suppose Joyce had bought 8 more pencils, so that the number of erasers and pencils bought be the same. This would mean that Joyce would spend $8 more than she would do for pencils in the original story, and as such, she would pay $12 more for pencils than erasers in this case (where she bought 8 more pencils than in the story).
Now, every one pencil cost $0.40 more than every one eraser. This is one group.
Because she spent $12 more on pencils than erasers, number of groups would be $12/$0.40 = 1200 cents / 40 cents = 30.
So in this case, she would have bought 30 pencils and 30 erasers.
In the original story, 8 of the pencils were not actually bought, so number of pencils bought
= 30 - 8
= 22
Ty
Alternatively, we can remove a few erasers instead using a very similar idea. This method is easier than using the unit-part technique (in my opinion).
Pencil: $1
Eraser: $0.60
Bought 8 more erasers than pencils
Spent $4 more on pencils than erasers
How many pencils?
A relatively easy way to do this is to make the number of pencils and erasers the same.
Suppose Joyce had bought 8 fewer erasers, so that the number of erasers and pencils bought be the same. This would mean that Joyce would spend $4.80 less than she would do for erasers in the original story, and as such, she would pay $8.80 more (because the pencils were $4 more than the erasers and now fewer erasers were bought so the difference is larger) for pencils than erasers in this case (where she bought 8 fewer erasers than in the story).
Now, every one pencil cost $0.40 more than every one eraser. This is one group.
Because she spent $8.80 more on pencils than erasers, number of groups would be $8.80/$0.40 = 880 cents / 40 cents = 22.
So in this case, she would have bought 22 pencils and 22 erasers.
In the original story, no pencil was removed, so she bought 22 pencils (and 30 erasers).
Pencil: $1
Eraser: $0.60
Bought 8 more erasers than pencils
Spent $4 more on pencils than erasers
How many pencils?
A relatively easy way to do this is to make the number of pencils and erasers the same.
Suppose Joyce had bought 8 fewer erasers, so that the number of erasers and pencils bought be the same. This would mean that Joyce would spend $4.80 less than she would do for erasers in the original story, and as such, she would pay $8.80 more (because the pencils were $4 more than the erasers and now fewer erasers were bought so the difference is larger) for pencils than erasers in this case (where she bought 8 fewer erasers than in the story).
Now, every one pencil cost $0.40 more than every one eraser. This is one group.
Because she spent $8.80 more on pencils than erasers, number of groups would be $8.80/$0.40 = 880 cents / 40 cents = 22.
So in this case, she would have bought 22 pencils and 22 erasers.
In the original story, no pencil was removed, so she bought 22 pencils (and 30 erasers).
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done
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I think this will be an easier way for you to understand the question! I hope you get it! (:
Date Posted:
4 years ago
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