Question 1067747
t=(mean1-mean2)/ sqrt {(s1^2/n1)+(s2^2/n2)}
=(76.4-81.2)/sqrt{8.2^2/90 + 7.6^2/100}
=-4.8/1.15=-4.17


the SE is sqrt {(s1^2/n1)+(s2^2/n2)}
8.2^2/90 + 7.6^2/100=1.325
sqrt of that is 1.15
98% CI for t df=188 is 2.34(1.15)=+/-2.69
This is added or subtracted to the mean
(-7.49, -2.11)