easy · GMAT Quant
Line 1 has 5 unit weights with mean 10 and standard deviation 2. Line 2 has 15 unit weights with mean 20 and standard deviation 4.
Treating each standard deviation as the population root-mean-square deviation from its group mean, what is the combined population standard deviation of all 20 observations?
- 3.00
- 58.14
- 3.50
- 5.63
- 10.00
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