I want to know what the margin of error is ? For b)

Question 12 of 16 - /1 E Plastic Microfiber Pollution on Shorelines In a study, we see that plastic microparticles are contaminating the world's shorelines and that much of the pollution appears to come from fibers from washing polyester clothes. The same study also took samples from ocean beaches. Five samples were taken from each of 18 different shorelines worldwide, for a total of 90 samples of size 250 mL. The mean number of plastic microparticles found per 250 mL of sediment was 18.3 with a standard deviation of 8.2. (a) Find a 90% confidence interval for the mean number of polyester microfibers per 250 mL of beach sediment. Round your answers to two decimal places. The 90% confidence interval is 16.86 to 19.74 eTextbook and Media (b) What is the margin of error? Round your answer to two decimal places. margin of error =