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KVPY2013MathematicsStatistics

In a city, the total income of all people with salary below Rs. 10000 per annum is less than the total income of all people with salary above Rs. 10000 per annum. If the salaries of people in the first group increases by 5 % and the salaries of people in the second group decreases by 5 % then the average income of all people

Options

  1. Aincreases
  2. Bdecreases
  3. Cremains the same
  4. Dcannot be determined from the data

Correct answer

B. decreases

Step-by-step solution

Let total number of people with salary below Rs. 10000 per annum is x and salary is A . Let total number of people with salary above Rs. 10000 per annum is y and salary is B then. xA - yB < 0 average after average before = x ( 105 100 A )+y ( 95 100 B ) x A+y B =1+ 5 100 ( x A-y B x A+y B )

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