Everyday Math

  • Concept of Proportion

    “A statement of equality of two ratios is called proportion” Four numbers a, b, c, d are said to be in proportion when the ratio first two a and b is equal to ratio of last two c and d.             i.e. or         a : b = c : d             e.g.      or         2 […]

  • Direct Proportion

    Suppose the price of one piece of soap is 20 Rs. If a person wants to buy one dozen pieces of soap, then he has to pay 240 Rs. If he wants to buy two dozen pieces of soap, he has to pay 480 Rs and so on. We can easily see that if the […]

  • Inverse Proportion

    Suppose that 20 men build a house in 6-days. If men are increased to 30 then they take 4-days to build the same house. If men become 40, they take 2-days to build the house. i.e. It can be seen that as the no. of men is increased, the time taken to build the house […]

  • Compound Proportion

    “The proportion involving two or more quantities is called Compound Proportion” Rules for Solving Compound Proportions CASE-1 If quantity 1 and quantity 2 are directly related and quantity 2 and quantity 3 are also directly related. Then we use the following rule CASE-2 If quantity 1 and quantity 2 are directly related and quantity 2 […]

  • Profit and Loss

    For the purpose of comparison, we usually express the actual profits or loss as a percentage of cost price. For example, a shopkeeper sold an article for Rs.60 which costs Rs.50 and another article sold for Rs.110 which cost Rs.100. In each case, shopkeeper makes a profit of Rs.10. It seems that in both cases […]

  • Concept of Discount

    It is usually seen that the retailers cannot sell defective items, old items, etc. at the retail-selling price. If these items are sold at lower price, then it is called sale price. The difference between marked price (selling price) and the sale price, is called discount. In other words, a reduction in the price of […]

  • Concept of Commission

    A commission is the payment, an agent gets for selling or buying something on behalf of another person. It is usually written as a percentage of cost price or selling price. Example: An agent got 2% commission on selling a plot for 1000000. Find his commission. Solution: Let       Sale Price = 1000000 Commission Rate […]

  • Concept of Rate

    Before defining rate, first we consider some examples. 1. If one dozen eggs cost 24 Rs., what is the cost of 1 egg? (Ans). One dozen eggs cost = 24 Rs             Cost of 1 egg = 24/12=2Rs/egg 2. A car travels 540 km consumed 60 liters petrol. Find distance travelled in liter. (Ans). In […]

  • Concept of Percentages

    Comparison of fractions is not an easy task, especially when the two fractions have different denominators. For example; if you are asked which of the fractions and is greater than the other. i.e. we want to compare, whether  is greater than or less than . Since, denominators of  and are different. To compare these fraction, […]

  • Expressing One Quantity as Percentage of Another Number

    In a school, 56 out of 70 teachers are female. What percentage of the teachers are females? What percentage of them is male? The fraction of female teachers in the school is 56/70 changing this fraction to percentage we have x 100% = 80% 80% of the teachers are female and percentage of male teachers […]

  • Percentage Changing

    The change in the value of an item can be expressed as a percentage increase or decrease of the original value. An increase of 5% in the salary of a men who earns Rs.500 per month. That means, there is an increase of Rs.5 For every hundred (100). i.e. after increase, Rs.100 becomes 105. Therefore, […]

  • Concept of Ratio

    Sometimes, we have to deal with the quantities whose comparison is required. Suppose in a class of 45-students, 15 of the students are girls, 30 of the students are boys, and then we can compare the number of boys with number of girls in two different ways. 1. There are 15 more boys than girls […]