Question: Biology and Environmental Science Carbon dioxide (CO2) is one of the primary gases contributing to the greenhouse effect and global warming. The mean amount of CO2 in the atmosphere for March 2013 was 397.34 parts per million (ppm).13 Suppose 40 atmospheric samples are selected at random in May 2013 and the standard deviation for CO2 in the atmosphere is σ = 20 ppm.
a. Find the probability that the sample mean CO2 level is less than 393 ppm.
b. Find the probability that the sample mean CO2 level is between 395 and 403 ppm.
c. Suppose the sample mean CO2 level is 400. Is there any evidence to suggest that the population mean CO2 level has increased? Justify your answer.