Home MATHEMATICS TOPIC 9: RATIO, PROFIT AND LOSS ~ MATHEMATICS FORM 1

TOPIC 9: RATIO, PROFIT AND LOSS ~ MATHEMATICS FORM 1

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Ratio
A ratio – is a way of comparing quantities measured in the same units
Examples of ratios
  1. A class has 45 girls and 40 boys. The ratio of number of boys to the number of girls = 40: 45
  2. A football ground 100 π‘š long and 50 π‘š wide. The ratio of length to the width = 100: 50
NOTE:Β Ratios can be simplified like fractions
  1. 40: 45 = 8: 9
  2. 100: 50 = 2: 1
A Ratio in its Simplest Form
Express a ratio in its simplest form
Example 1
Simplify the following ratios, giving answers as whole numbers
Screen Shot 2016 06 08 At 15.38.43 1465389584390
Solution
Screen Shot 2016 06 08 At 15.40.47 1465389677439
A Given Quantity into Proportional Parts
Divide a given quantity into proportional parts
Example 2
Express the following ratios in the form of
Screen Shot 2016 06 08 At 15.46.27 1465390024092
Solution
Screen Shot 2016 06 08 At 15.49.44 1465390210793
To increase or decrease a certain quantity in a given ratio, multiply the quantity with that ratio
Example 3
  1. Increase 6 π‘š in the ratio 4 ∢ 3
  2. Decrease 800 /βˆ’ in the ratio 4 ∢ 5
Solution
Screen Shot 2016 06 08 At 15.56.23 1465390605588
Simple Interest
Calculate simple interest
The amount of money charged when a person borrows money e. g from a bank is called interest (I)
The amount of money borrowed is called principle (P)
To calculate interest, we use interest rate (R) given as a percentage and is usually taken per year or per annum (p.a)
Screen Shot 2016 06 08 At 16.15.55 1465391834547
Example 6
Calculate the simple interest charged on the following
  1. 850, 000/βˆ’ at 15% per annum for 9 months
  2. 200, 000/βˆ’ at 8% per annum for 2 years
Solution
Screen Shot 2016 06 08 At 16.19.14 1465391982423
Real Life Problems Related to Simple Interest
Solve real life problems related to simple interest
Example 7
Mrs.
Mihambo deposited money in CRDB bank for 3 years and 4 months. A t the
end of this time she earned a simple interest of 87, 750/βˆ’ at 4.5% per
annum. How much had she deposited in the bank?
Solution
Given I = 87, 750/βˆ’ R = 4.5% % T = 3 years and 4 months
Change months to years
Screen Shot 2016 06 08 At 16.30.40 1465392677105

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