Mercury Is a Heavy Metal That Can Cause Severe Health $\mathrm { f }$

Multiple Choice

Mercury is a heavy metal that can cause severe health problems in even small concentratiı Fish and shellfish efficiently concentrate mercury into their flesh, so it is important to mo seafood for its mercury content.

An extensive study conducted in 1980 concluded that the mean mercury level in oysters $\mathrm { f }$ White Bear estuary was $0.020$ parts per million (ppm) with a standard deviation $\sigma = 0.022$ ppm. In 2012 , a sample of 48 oysters from the same estuary exhibited a mean mercury concentration of $0.004$ ppm.

Can you conclude that the 2012 mercury concentration is lower than in 1980 ? Use the $\alpha = 0.01$ level of significance. ns.

A) No. There is insufficient evidence to conclude that the mercury concentration has decreased from 1980 to 2012.
B) Yes. The mercury concentration appears to be lower in 2012.
C) There is not enough information to reach a conclusion.