Question 597928
( xbar - z*sigma/sqrt(n), xbar + z*sigma/sqrt(n) )


( 230 - 1.95996*10.4/sqrt(71), 230 + 1.95996*10.4/sqrt(71) ) ... Note: use a table or a calculator to find the value of z


(227.58091, 232.419086)


So the 95% confidence interval is (227.58091, 232.419086)