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JEE Main20241 Feb 2024Morning ShiftMathematicsStatisticsActual

Let the median and the mean deviation about the median of 7 observation 170 , 125 , 230 , 190 , 210 , a , b be 170 and 205 7 respectively. Then the mean deviation about the mean of these 7 observations is:

Options

  1. A31
  2. B28
  3. C30
  4. D32

Correct answer

C. 30

Step-by-step solution

Given observations are 125 , a , b , 170 , 190 , 210 , 230 . Median = 170 Mean deviation about median is 205 7 . ⇒ 205 7 = 0 + 45 + 60 + 20 + 40 + 170 − a + 170 − b 7 ⇒ a + b = 300 Mean = 170 + 125 + 230 + 190 + 210 + a + b 7 = 175 Mean deviation about mean = 50 + 175 − a + 175 − b + 5 + 15 + 35 + 55 7 = 30

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