Ratio: For comparing two ratios, we need to convert them to like fractions. When the two fractions are equal, then the two given ratios are equal.
Proportion: If two ratios are equal then given four quantities are said to be in proportion.
Converting fractions or decimals into percentage: For this, multiply the given fraction or decimal by 100.
Converting percentage into fractions or decimals: For this, divide the given percentage by 100.
Simple Interest: When P is principal, r is the rate of interest per annum and t is the time in years, then simple interest is given by following formula:
`SI = (P xx r xx t) ÷ 100`
`P = (SI xx 100)/ (r xx t)`
`r = (SI xx 100)/(P xx t)`
`t = (SIxx 100)/(P xx r)`
Profit percentage `= (text(Profit)xx 100)/text(Cost Price)`
Loss percentage `= (text(Loss) xx 100)/ text(Cost Price)`
Cost Price `= (text(Selling Price) xx 100)/(100 + %text(Profit))`
Cost Price `= (text(Selling Price) xx 100)/(100 - %text(Loss))`
Question 1: Find the ratio of:
Question 2: In a computer lab, there are 3 computers for every 6 students. How many computers will be needed for 24 students?
Answer: Since, every 6 students need 3 computers.
Hence, every 1 student needs 3 ÷6 computers.
Hence, every 24 students need `(3 ÷ 6) xx 34 = 12` computers
Question 3: Population of Rajasthan = 570 lakhs and population of UP = 1660 lakhs. Area of Rajasthan = 3 lakh km2 and area of UP = 2 lakh km2.
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