#### Answer

The mean is 11.05, mode: 20.5, the median is 9.5, the midrange is 11.75.

#### Work Step by Step

The mean can be counted by summing all the data and dividing it by the number of data: $\frac{3+6.5+6+5.5+20.5+7.5+12+20.5+11.5+17.5}{10}=11.05$, the mean is 11.05. The mode is the data occuring the most times which here is 20.5 appearing twice. The median is the average of the 1 or 2 (here 2) middle data: (11.5+7.5)/2=9.5, the median is 9.5. The midrange is the average of the highest and the lowest data: (20.5+3)/2=11.75, the midrange is 11.75. That data seem to be rounded to the closest 0.5, but we cannot deduce any meaning of these data because we do not know the limit of something being safety or not.