Biology and Environmental Science The amount of chlorophyll near Stearns Wharf in Santa Barbara, California, varies due to the seasons, the entry of fresh water into the area, and the salt water from the ocean. A random sample of 35 days was selected and the chlorophyll near Stearns Wharf was
The sample mean chlorophyll concentration was
Assume the population standard deviation is
a. Find a 98% confidence interval for the true mean chlorophyll concentration near Stearns Wharf.
b. Find the sample size necessary to construct a 98% confidence interval for the true mean chlorophyll concentration with a bound on the error of estimation B = 0.5.
Parrot Jungle Island is a roadside attraction in Miami, Florida, featuring tropical birds, crocodiles, and over 2000 varieties of plants and flowers. A new advertising campaign was developed to attract more out-of-state visitors. In a random sample of 270 visitors, 189 were area residents.
a. Find the sample proportion of visitors who were area residents. Check the nonskewness criterion.
b. Find a 99% confidence interval for the true proportion of visitors who were area residents.
c. Suppose no prior knowledge of the proportion of visitors who were area residents is available. Find the sample size necessary for a 99% confidence interval with a bound on the error of estimation of 0.05.