Continuing with the same stream, if the stream empties into the James River and

Question

Continuing with the same stream, if the stream empties into the James River and carries copper at a concentration of 65 + 3 ppb, how many grams of copper does it inject into the James River in an hour? Again, include the appropriate uncertainty. (4 pts) 3. Tuna are prone to be contaminated with fairly high levels of mercury due to their position at the top of the marine food chain. Typical concentrations of mercury in tuna range from 200 to 400 ppb. Assume that the concentration of mercury in tuna exhibits a normal distribution with a mean of 325 ppb and a standard deviation of 75 ppb. Use the area table from your text (or handout) to answer the following questions. (6 pts) What fraction of tuna have mercury concentrations greater than 450 ppb? What fraction of tuna have mercury concentrations between 250 and 350 ppb?

Explanation / Answer

If we plot the mercury level as a normal distribution plot, sith mean at 325ppb and standard deviation as 75pp be, we can use the area table, to calculate the percentage of tuna between any given interval.

So % of tuna with Hg level above 450ppb is 4.78% of the population.

The % of tuna with Hg levels between 250 ppb and 350 ppb is 47.19%

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