Chpt 3 - Percentage

PERCENTAGE Mathematics Preparatory Course for Direct Entry to Higher Nitec 3-1 CHAPTER 3 3.1 PERCENTAGE Percentages are used as a means of comparison. This comparison is based on 100 parts. Remember that "per cent" means "per hundred". So, 60% really means 60 out of 100. Any percentage can be converted to a fraction or to a decim al. To convert a percentage to a fraction: 1 Drop the per cent sign. 2 Write the number over 100. 3 Reduce the fraction form ed to its lowest terms. To convert a percentage to a decimal: 1 Drop the per cent sign. 2 Move the decimal point in the number t wo places to the left. Example 1 Write each percentage as a fraction in its lowest terms. (a) 4 1 % (b) 33 3 1 % Example 2 Express each percentage as a decimal: (a) 7 % (b) 35.8 % Sometimes it is necessary to convert a fraction or decimal to a percentage. This can be done easily. To convert a fraction or decimal to a percentage: Example 3 Express the following number as percentages: (a) 6 1 (b) 0.08

PERCENTAGE Mathematics Preparatory Course for Direct Entry to Higher Nitec 3-2 3.2 CALCULATING PERCENTAGES Many problems which involve percentage require finding a certain percentage of a given number. But other problems require expressing one number as a percentage of another number. Sometimes you must also find a number if the value of a percentage of the number is known. Exampl e 4 In a group of 90 people, 23 are Malays, 13 are Indians and the rest are Chi nese. What i s the percentage of Chi nese? Example 5 In a group of people, 45% are men, 30% are women and the rest are children. If there are 15 children in the group, how many men are there? 3.3 MONEY TRANSACTIONS INVOLVING PERCENTAGES I n a sal e, a discount (reduction) in price is given. Suppose an item is priced at $50. This is called the usual price of the item. If there is a discount of $6 during a sale, the item will cost $44. This reduced pri ce i s cal l ed the sale pr ice. Sale pr ice = Usual price – Discount A discount is often expressed as a percentage of the usual price. Example 6 The usual price of a pair of shoes i s $35. A t a sal e, they were sol d at a discount of 10%. What was the sal e pri ce?

PERCENTAGE Mathematics Preparatory Course for Direct Entry to Higher Nitec 3-3 Example 7 The sale price of a camera after a 15% discount is $255. Find its usual price. 3.4 PROFIT AND LOSS Suppose a shopkeeper buys an item for $70 and sells it for $90. The price at which he buys the ite m is ca lled the cost price and the pri ce at whi ch he sel l s i t i s cal l ed the s e lling price . Si nce the selling price ($90) is greater than the cost price ($70), the shopkeeper earns $20. The amount of money earned is called the profit or gain. If the shopkeeper had sold the item for $65, then he would have lost $5. The amount of mo