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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. |
| 4. | Entry fee in an examination was Re. 1. Later, this was reduced by 25% which increased the sale by 20%. The percentage increase in the number of visitors is |
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| 5. | In an election between two candidates, one got 55% of the total valid votes, 20% of the votes were invalid. If the total number of votes was 7500, the number of valid votes that the other candidate got was |
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| 6. | From a container having pure milk, 20% is replaced by water and the process is repeated thrice. At the end of the third operation, the milk is |
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