What is the mode, median, and mean of 3, 12, 11, 7, 5, 5, 6, 4, 10?

Mode is ##5##, median is ##6## and mean is ##7##.
Let us write the given data points in increasing order. These are
##{3,4,5,5,6,7,10,11,12}##
Now mode is the data point which appears most time and it is clearly ##5##.
Median is the data point which appears exactly in the center when data is arranged in increasing order. As there are ##9## data points already arranged in increasing order, median is the value of middle i.e ##5^(th)## data point (equal to ##(9+1)/2=5##. Hence median is ##6##.
Mean is the arithmetic average which is ##1/9(3+4+5+5+6+7+10+11+12)=1/9xx63=7##
Hence, Mode is ##5##, median is ##6## and mean is ##7##.