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Problem 3
9.1 Z-Interval to Compare Two Population Means: Independent Samples
A researcher theorized that average heights of boys and girls of the same age prior to undergoing puberty should be the same. Fifty-eight randomly selected boys of age 8 had an average height of 123.5 cm with a variance of 98cm. Fifty-five randomly selected girls had an average height of 126.1 cm with a variance of 119cm. Find the 99% confidence interval for the true mean difference between boys and girls heights at age 8. Is there a significant difference?