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NDA 2020
Exam
NDA
Year
2020
Subject
Mathematics
Chapter
Statistics

NDA 2020 · Mathematics · Statistics

A data set of n observations has mean 2 M , while another data set...

A data set of nn observations has mean 2M2 M, while another data set of 2n2 n observations has mean MM. What is the mean of the combined data sets?

Options

  1. AMM
  2. B3M2\frac{3 M}{2}
  3. C2M3\frac{2 M}{3}
  4. D4M3\frac{4 M}{3}

Correct answer

D. 4M3\frac{4 M}{3}

Step-by-step solution

Sum of nn observation =2M×n=2 M \times n Sum of 2n2 n observation =M×2n=M \times 2 n Mean of combined data sets =2Mn+2Mn(n+2n)=43M=\frac{2 M n+2 M n}{(n+2 n)}=\frac{4}{3} M.
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