Answer
The mean is 1.88, no mode, the median is 2, the midrange is 2.5.
Work Step by Step
The mean can be counted by summing all the data and dividing it by the number of data: $\frac{4+6\cdot3+7\cdot2+11\cdot1}{25}=1.88$, the mean is 773.667. The mode is the data occuring the most timesand here it is 1, appearing 11 times. The median is the average of the 1 or 2 (here 1) middle data: (2)/1=2, the median is 2. The midrange is the average of the highest and the lowest data: (4+1)/2=2.5, the midrange is 2.5. The measures of centres can be obtained but because the numbers do not have numerical values, the measures of centres do not have any real meaning.