I don't really understand why I'm not getting the correct answers, especially for the margin of error. Please walk me through step by step what I could be doing wrong please!?

We have the survey data on the body mass index (BMI) of 642 young women. The mean BMI in the sample was )7 = 26.6. We treated these data as an SRS from a Normally distributed population with standard deviation 0 = 8.6. Give condence intervals for the mean BMI and the margins of error for 90%, 95%, and 99% condence. (Round your answers to two decimal places.) Condence Level Interval margin of error 90% i26.04 to 127.16 l 0.48 x 95% 4 to m 0.57 x 99% E to 27.43 i v 0.75 x How does increasing the condence level change the margin of error of a condence interval when the sample size and population standard deviation remain the same? 0 Increasing the condence level causes the margin of error to increase. O Increasing the condence level causes the margin of error to decrease. 0 Increasing the condence level doesn't affect the margin of error. u! You may need to use the appropriate Appendix Table to answer this question. The National Institute of Standards and Technology (NIST) supplies "standard materials" whose physical properties are supposed to be known. For example, you can buy from NIST an iron rod whose electrical conductivity is supposed to be 10.1 at 293 kelvin. (The units for conductivity are microsiemens per centimeter. Distilled water has conductivity 0.5.) Of course, no measurement is exactly correct. NIST knows the variability of iis measurements very well, so it is quite realistic to assume that the population of all measurements of the same rod has the Normal distribution with mean [1 equal to the true conductivity and standard deviation 0 = 0.1. Here are six measurements on the same standard iron rod, which is supposed to have conductivity 10.1. 10.07 9.88 10.02 10.14 10.21 10.11 NIST wants to give the buyer of this iron rod a 90% condence interval for its true conductivity. What is this interval? (Round your answers to three decimal places.) 9.989 x to 10.151 X microsiemens per centimeter You may need to use the appropriate Appendix Table to answer this