Question: Heights of 9 year old girls. At age 9, the average weight (21.3 kg) and average height (124.5cm) for both boys and girls are exactly the same. A random sample of 9 year olds yielded these results. Estimate the mean difference in height between boys and girls with 95% confidence. Does your interval support the given claim?

Boys Girls

Sample size 60 50

Mean height, cm 123.5 126.2

Population variance 98 120