hard · GMAT Quantitative Reasoning
Plant North has 10 defect counts with mean 20 and standard deviation 4. Plant South has 20 defect counts with mean 30 and standard deviation 6.
Treating each standard deviation as the population root-mean-square deviation from its group mean, what is the combined population standard deviation of all 30 observations?
- 160.67
- 10.00
- 5.33
- 7.18
- 5.00
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