Final answer:
The most appropriate measure to summarize the given data is the mean.
So, the correct answer is option 1) mean.
Step-by-step explanation:
To summarize the given data, the most appropriate measure to use is the mean. The mean is calculated by adding up all the values and dividing by the total number of values. In this case, we add up all the numbers of email advertisements and divide by 9 (the total number of days).
Mean = (40 + 41 + 42 + 43 + 46 + 48 + 50 + 52 + 85) / 9 = 447 / 9 = 49.67
Therefore, the mean number of email advertisements Lena has received per day is approximately 49.67.
So, the correct answer is option 1) mean.