medium · GMAT Quant
Shift A has 7 hourly output scores with mean 14 and standard deviation 4. Shift B has 14 hourly output scores with mean 21 and standard deviation 7.
Treating each standard deviation as the population root-mean-square deviation from its group mean, what is the combined population standard deviation of all 21 observations?
- 6.00
- 5.50
- 6.99
- 7.00
- 174.14
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