Python:

# create a 10-by-10 matrix with random numbers sample from a standard normal dist.

# calculate mean values of each column

# calculate mean of each row

# calculate max value of each row

# calculate min value of each column

# calculate min value of the whole matrix

# assign all elements from the 8th and the 9th columns of this matrix into a new matrix

# (so the dimension of new matrix will be 10-by-2)

# calculate the mean value of the new matrix (all elements)