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Question
primary 5 | Maths
| Percentage
3 Answers Below
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Pls help. Tks
Date Posted: 2 years ago
Views: 466
80 - 46 = 34
50% = 50/100 = ½, 25% = 25/100 = ¼
So ½ of the 20¢ coins and ¼ of the 50¢ coins are used.
To make things easier, let total number of 20¢ coins be 2 units and total number of 50¢ coins be 4 parts.
46 coins = 2 units + 3 parts
34 coins (the remaining coins) = 2 units + 1 part
Their Difference = 2 parts
But their difference also = 46 - 34 = 12
So 2 parts = 12
1 part = 12 ÷ 2 = 6
Total Number of 50¢ coins
= 4 parts = 4 × 6 = 24
Percentage of coins in the box that are 50¢
= (24/80 × 100) %
= (3/10 × 100) %
= 30%
50% = 50/100 = ½, 25% = 25/100 = ¼
So ½ of the 20¢ coins and ¼ of the 50¢ coins are used.
To make things easier, let total number of 20¢ coins be 2 units and total number of 50¢ coins be 4 parts.
46 coins = 2 units + 3 parts
34 coins (the remaining coins) = 2 units + 1 part
Their Difference = 2 parts
But their difference also = 46 - 34 = 12
So 2 parts = 12
1 part = 12 ÷ 2 = 6
Total Number of 50¢ coins
= 4 parts = 4 × 6 = 24
Percentage of coins in the box that are 50¢
= (24/80 × 100) %
= (3/10 × 100) %
= 30%
b)
Total umber of 20¢ coins = 80 - 24 = 56
Number of 20¢ coins used
= 56 × ½ = 28
Number of 50¢ coins used = 1 part = 6
Cost of storybook
= 28 × 20¢ + 6 × 50¢
= 560¢ + 300¢
= 860¢
= $8.60
Total umber of 20¢ coins = 80 - 24 = 56
Number of 20¢ coins used
= 56 × ½ = 28
Number of 50¢ coins used = 1 part = 6
Cost of storybook
= 28 × 20¢ + 6 × 50¢
= 560¢ + 300¢
= 860¢
= $8.60
See 3 Answers
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Hi there! Wow, this question is pretty tough, but I hope this helps:) I think drawing a model really helps with this question since it helps you visualise the fraction of coins used. Most important thing would be to realise that the number of 20 cent coins used and left are the same, since 50% of 20 cent coins are used. So any difference in the number of coins after would come from the difference in 50 cent coins. Do let me know if this helped!
Date Posted:
2 years ago
Thanks. But seems like not correct. A should be 30% and b is $8.60.
Not correct.
12 coins represent 50% of the 50¢ coins, not 25%. See main question's comments section for my working.
12 coins represent 50% of the 50¢ coins, not 25%. See main question's comments section for my working.
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Rough idea
Date Posted:
2 years ago
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Rough idea
Date Posted:
2 years ago
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