Percentages are used to express how large one quantity is, relative to another quantity. The first quantity usually represents a part of, or a change in, the second quantity which should be greater than zero.
For example, an increase of $ 0.15 on a price of $ 2.50 is an increase by a fraction of 0.15 / 2.50 = 0.06. Expressed as a percentage, this is therefore a 6% increase.
Percentages are correctly used to express fractions of the total. For example, 25% means 25 / 100, or one quarter, of some total.
Percentages larger than 100 can be meant literally (such as "a family must earn at least 125% over the poverty line to sponsor a spouse visa").
Here are other examples:
- What is 200% of 30?
Answer: 200% × 30 = (200 / 100) × 30 = 60.
- What is 13% of 98?
Answer: 13% × 98 = (13 / 100) × 98 = 12.74.
- 60% of all university students are male. There are 2400 male students. How many students are in the university?
Answer:400 = 60% × X, therefore X = (2400 / (60 / 100)) = 4000.
- What is 13 of 20?
Answer:13/20=65/100=65%
- A stall selling clothes of with a discount of 50% had no people buying its clothes,so it increased its discount to 99%. The original price of a piece of clothing is $200.
(a)What is its first discounted price?
(b)What is its final discounted price?
Answer= (a) 1/2 x $200=$100
(b) 1/100x $200 = $2
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