Plastic Microfiber Pollution on Shorelines
In a study, we see that plastic microparticles are contaminatingthe world’s shorelines and that much of the pollution appears tocome from fibers from washing polyester clothes. The same studyalso took samples from ocean beaches. Five samples were taken fromeach of 18 different shorelines worldwide, for a total of 90samples of size 250 mL. The mean number of plastic microparticlesfound per 250 mL of sediment was 18.3 with a standard deviation of8.2 .
(a) Find a 90% confidence interval for the mean number ofpolyester microfibers per 250 mL of beach sediment.
Round your answers to two decimal places.
The 90% confidence interval is
(b) What is the margin of error?
Round your answer to two decimal places.
margin of error =
(C) If we want a margin of error of only ±1 with 90% confidence,what sample size is needed?
Round your answer up to the nearest integer.
sample size =
