hard · GMAT Quantitative Reasoning
Cohort Red has 6 latency readings with mean 12 and standard deviation 3. Cohort Blue has 9 latency readings with mean 18 and standard deviation 5.
Treating each standard deviation as the population root-mean-square deviation from its group mean, what is the combined population standard deviation of all 15 observations?
- 6.00
- 72.04
- 5.22
- 4.00
- 4.20
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