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Concepts of Percentage : By a certain percent, we mean that many hundredths. Thus, x percent means x hundredths, written as x%. To express x% as a fraction : we have, x% = x/100. To express a/b as a percent : we have, a/b = (a/b×100)% . |
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Results on population : Let the population of a town be P now and suppose it increases at the rate of R% per annum, then : Population after n years = P[1+R/100]n. Population n years = p / [1+R/100]n. |
| 1. | Express each of the following as a decimal. 28% |
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| Sol. = 28/100 = 0.28%. | |
| 2. | Express each of the following as a decimal. 0.04% |
| Sol. = 0.04/100 = 0.0004%. | |
| 3. | Express each of the following as a fraction. 4% |
| Sol. = 4/100 = 1/25. |
| 7. | How many litres of pure acid are there in 8 litres of a 20% solution? |
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| 8. | When 15% is lost in grinding wheat, a country can export 30 lakh tons of wheat. On the other hand, if 10% is lost in grinding, it can export 40 lakh tons of wheat. The production of wheat in the country is |
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| 9. | Two students appeared at an examination. One of them secured 9 marks more than the other and his marks was 56% of the sum of their marks. The marks obtained by them are |
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