MATHS PERCENTAGES

kitty

2010-01-29 4:15 am

1)The price of petrol has increased by 11 %.A man has reduced his consumption by 20 %.Find the percentage increase or decrease in the man&#039;s expenditure.

2)The marked price of an article is 30% higher than its cost.If the article is sold at a discount of 30% on the marked price,find the percentage gain or loss in selling this article.

回答 (1)

用戶9112

2010-01-29 4:23 am

✔ 最佳答案

(1) Expenditure is proportional to Consumption * Price
When the price is increased by 11% and consumption reduced by 20%, the new expenditure = Old Expenditure * (1 + 11%) * (1 – 20%)
= Old Expenditure * 1.11 * 0.8
= Old Expenditure * 0.888
Percentage decreased in expenditure
= (Old Expenditure – 0.888 Old Expenditure)/ Old Expenditure * 100%
= 11.2%
(2) Marked price = Cost * (1 + 30%) = 1.3 * Cost
Selling price = Marked price * (1 – 30%)
= 1.3 * Cost * 0.7
= 0.91 * Cost
Percentage loss = (Cost – 0.91* Cost)/ Cost * 100%
= 9%

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