5. The oxygen saturation of a lake is found by dividing the amount of dissolved oxygen the lake water currently has per liter by the dissolved oxygen capacity per liter of the water, and then converting that number into a percent. If the lake currently has 6.4 milligrams of dissolved oxy- gen per liter of water and the dissolved oxygen capacity is 9.5 milligrams per liter, what is the oxygen saturation level of the lake, to the nearest percent?

To calculate the oxygen saturation level of the lake, you can use the formula: \[ \text{Oxygen Saturation} = \left( \frac{\text{Current Dissolved Oxygen}}{\text{Dissolved Oxygen Capacity}} \right) \times 100 \] Given: - Current Dissolved Oxygen = 6.4 mg/L - Dissolved Oxygen Capacity = 9.5 mg/L Now, plug in the values: \[ \text{Oxygen Saturation} = \left( \frac{6.4}{9.5} \right) \times 100 \] Calculating the fraction: \[ \frac{6.4}{9.5} \approx 0.6737 \] Now, multiply by 100 to convert to a percentage: \[ 0.6737 \times 100 \approx 67.37 \] Rounding to the nearest percent, the oxygen saturation level of the lake is: \[ \text{Oxygen Saturation} \approx 67\% \] Thus, the oxygen saturation level of the lake is **67%**.