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Maharashtra State BoardSSC (English Medium) 9th Standard

Mean of 100 observations is 40. The 9th observation is 30. If this is replaced by 70 keeping all other observations same, find the new mean.

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Question

Mean of 100 observations is 40. The 9th observation is 30. If this is replaced by 70 keeping all other observations same, find the new mean.

Options

  • 40.6

  • 40.4

  • 40.3

  • 40.7

MCQ
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Solution

40.4

Explanation:

We have,

Mean of 100 observations is 40.

Total sum of observations = 100 × 40 = 4000

If the 9th observation is 30 and is replaced by 70 keeping all other observations same.

New, total sum of observations = 4000 - 30 + 70 = 4040

So, the new mean = `4040/100` = 40.4

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Chapter 7: Statistics - Problem Set 7 [Page 126]

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Balbharati Mathematics 1 [English] Standard 9 Maharashtra State Board
Chapter 7 Statistics
Problem Set 7 | Q (1) (vii) | Page 126

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