A speech class has $4$ freshmen and $3$ sophomores. (Everyone is distinguishable.) In how many ways can they stand in line, so that all the sophomores are standing together?
The sophomores can occupy any one of 5 positions
For each of these they can be arranged in 3! = 6 ways
And for each of these the freshmen can be arranged in 4! = 24 ways
So
5 * 6 * 24 = 720 arrangements
+1911 
