1.
a. Calculates the sum of all things in m that are greater than 5.
- m > 5 returns a 1 for all entries that are greater than 5 and a 0 for the others
- m(m > 5) returns a new matrix only containing those values that were greater than 5

b. Calculates the sum of all things in m that are greater than 5.
- m .* (m > 5) will be a matrix the same size as m, but with all of the entries that were not > 5 will be zero. Taking the sum twice of this matrix then gives us overall sum of these values.

c. The number of entries in m where the value squared is greater than 5.  '.*' has a higher precedence than '>' so we first multiply each value in m by itself (i.e. square it) than see if that value is > 5.