What is the mean NOX emission (g/km)?

What is the mean NOX emission (g/km)?

• A. 0.063 g/km
• B. 0.0063 g/km
• C. 0.263 g/km
• D. 0.126 g/km

Answer: (A)

The mean NOX emission per kilometer is the average amount of nitrogen oxides produced for each kilometer driven across all the tested vehicles. To get it, you add up all the NOX values (in g/km) and divide by how many measurements you have. For example, if you had a few cars with NOX values around 0.05–0.08 g/km, the mean would fall in that range. 0.063 g/km means, on average, 63 mg of NOX are emitted for each kilometer traveled. That’s a plausible average for a dataset of vehicle emissions. The other numbers would correspond to notably smaller or larger averages: 0.0063 g/km is about 6.3 mg/km, which is much lower; 0.126 g/km is about double this mean; 0.263 g/km is far higher.

The mean NOX emission per kilometer is the average amount of nitrogen oxides produced for each kilometer driven across all the tested vehicles. To get it, you add up all the NOX values (in g/km) and divide by how many measurements you have. For example, if you had a few cars with NOX values around 0.05–0.08 g/km, the mean would fall in that range.

0.063 g/km means, on average, 63 mg of NOX are emitted for each kilometer traveled. That’s a plausible average for a dataset of vehicle emissions. The other numbers would correspond to notably smaller or larger averages: 0.0063 g/km is about 6.3 mg/km, which is much lower; 0.126 g/km is about double this mean; 0.263 g/km is far higher.