Data on fifth-grade test scores (reading and mathematics) for 420 school districts in California yield = 646.2 and standard deviation sY = 19.5.
(a) Construct a 95% confidence interval for the mean test score in the population.
(b) When the districts were divided into districts with small classes (

Is there statistically significant evidence that the districts with smaller classes have higher average test scores? Explain.

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Class Size Average Score Standard Deviation (sy) n Small Large 657.4 19.4 238 650.0 17.9 182