medium · GMAT Quant
A manufacturing plant tests material strength across three independent sub-samples of components, all produced with the same mean tensile strength. Sub-sample A (n_1 = 4) has s_1^2 = 10, Sub-sample B (n_2 = 6) has s_2^2 = 15, and Sub-sample C (n_3 = 11) has s_3^2 = 20.
What is the pooled sample variance s_p^2 across all 21 components?
- dfrac30518
- 15
- dfrac1759
- dfrac30520
- dfrac503
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