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primary 5 | Maths
| Rate & Ratio
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Hi need help please. Thank you
Date Posted: 2 years ago
Views: 493
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By Guesswork,
there were 7 more rulers than pencils.
17 rulers cost $6.80, 10 pencils cost $7, difference=$0.20
18 rulers cost $7.20, 11 pencils cost $7.7, diff=$0.50
...
20 rulers cost $8.00, 13 pencils cost $9.10, difference is $1.10.
By Calculation:
Ken bought 'p' number of pencils and 'r' number of rulers
p*$0.70 - r*0.40 = $1.10
p + 7 = r
p*0.7 - 0.4 p - 0.4*7 =1.1
0.3 p =1.1+2.8=3.9
p =39/3 = 13 pencils
r = p+7 = 20 rulers
b) 20*$0.40=$8
there were 7 more rulers than pencils.
17 rulers cost $6.80, 10 pencils cost $7, difference=$0.20
18 rulers cost $7.20, 11 pencils cost $7.7, diff=$0.50
...
20 rulers cost $8.00, 13 pencils cost $9.10, difference is $1.10.
By Calculation:
Ken bought 'p' number of pencils and 'r' number of rulers
p*$0.70 - r*0.40 = $1.10
p + 7 = r
p*0.7 - 0.4 p - 0.4*7 =1.1
0.3 p =1.1+2.8=3.9
p =39/3 = 13 pencils
r = p+7 = 20 rulers
b) 20*$0.40=$8
Date Posted:
2 years ago
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