Hint: Consider what the new point estimate is and whether its higher or lower.
I know what to do for (A) but i have no idea what (B) is asking me... can anyone enlighten me??? BTW the interval and the answer that I got for (A) is (223.98, 224.03).. I interpret this by saying that we are 90% confident that the interval from 223.96 to 224.03 captures the true mean dimension in millimeters
(B) confused me