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upteto17 q129

0. The number of observations in a survey is 40. If the mean of the first 10 observations is 4.5 and that of remaining is 3.5, then the mean of the whole survey is

  • Option : C
  • Explanation : (C) Given, number of observation in a survey is 40.
    Sum of first 10 observation = 10 × 4.5 = 45
    and sum of remain 30 observation = 3.5 × 30 = 105
    Sum of 40 observation = 105 + 45 = 150
    ∴ Mean of 40 observation = 150/40 = 3.75
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