Answer: 4.5
Step-by-step explanation:
The given data set : 5, 3, 5, 30, 4, 5, 4, 3, 4, 5
It can be seen that it contains an outlier (30), then the best measure of center for this data set is median value. [∵ Mean gets affected by outlier extremely.]
First arrange data in an order : 3, 3 ,4 ,4 ,<u>4 ,5</u> ,5 ,5 ,5 ,30
Since , the number of data values =10 (Even)
Then, Median = Mean of the middle two values
i.e. Median = 
Hence, the best measure of center for this data set is 4.5 .