The most appropriate measure of center for this data would be the median of 49.
The reason for this is that the data is skewed, with a cluster of higher donations between 45 and 50, and only a few donations in the lower range. The mean can be affected by outliers, and in this case, the presence of the two donations of 11 and 18 can skew the mean downwards. Therefore, the median, which is the middle value of the data set when arranged in order, is a more appropriate measure of center for this skewed distribution.
In this case, the median of 49 represents the middle value of the data set and is not influenced by the extreme values at either end of the distribution. Therefore, the charity can use the median donation amount of 49 dollars to accurately represent the typical donations received.