To find the mean of the given data set for the number of online transactions made per day over the past 8 days, we need to follow these steps:
1. List the data points: The transactions are:
[tex]\[
69, 69, 55, 91, 63, 83, 71, 87
\][/tex]
2. Sum the data points: Add all the transaction numbers together:
[tex]\[
69 + 69 + 55 + 91 + 63 + 83 + 71 + 87
\][/tex]
3. Calculate the sum:
[tex]\[
69 + 69 = 138 \\
138 + 55 = 193 \\
193 + 91 = 284 \\
284 + 63 = 347 \\
347 + 83 = 430 \\
430 + 71 = 501 \\
501 + 87 = 588
\][/tex]
4. Count the number of data points: There are 8 transactions in total.
5. Find the mean: Divide the sum of the transactions by the number of data points:
[tex]\[
\text{Mean} = \frac{\text{Sum of transactions}}{\text{Number of transactions}} = \frac{588}{8} = 73.5
\][/tex]
6. Round the mean: Since the mean is already at one decimal place, there is no need for further rounding.
Therefore, the mean of this data set, rounded to one decimal place, is [tex]\( \boxed{73.5} \)[/tex].