A consumer group tested the battery life of 150 smartphones. The average battery life in the sample was found to be 18.5 hours, with a margin of error of 1.2 hours. Which of the following statements best interprets this finding?
Plausible values for the average battery life are between 17.3 hours and 19.7 hours.
The average battery life of all smartphones is less than 17.3 hours.
The average battery life of all smartphones is greater than 19.7 hours.
The average battery life of all smartphones is exactly 18.5 hours.
