Question

1. base your answer on the graph below shows the amount of mercury measured during the last 10 years in a river that provides the water supply for a city. if water that contains more than 5×10^(-3) gram of mercury per liter (g/l) is considered unsafe, what is the best inference that can be made from this graph? a) the safety of the water cannot be determined. b) the water has been unsafe since 1988. c) the water will become unsafe within 5 years. d) the water will continue to be safe for at least 10 years.

Explanation:

The graph shows the mass of mercury in the river water over 10 - year period. The safety threshold is $5\times10^{- 3}\text{ g/L}$. By observing the graph, we can see that the mass of mercury reaches $5\times10^{-3}\text{ g/L}$ around 1988. After 1988, the mass of mercury continues to increase, indicating that the water has been above the unsafe level since then.

Answer:

B. The water has been unsafe since 1988.