medium · GMAT Quant
A clinical trial evaluates blood pressure variance across two patient cohorts with the same average baseline blood pressure. Cohort X has n_X = 6 patients with a sample variance s_X^2 = 40, and Cohort Y has n_Y = 16 patients with a sample variance s_Y^2 = 70.
What is the pooled sample variance of the two cohorts combined?
- 62.5
- 55
- 1250
- 56.8
- 61.8
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