【Example 7】10 students line up and walk, requiring that 4 female students be adjacent, and neither walk at the very front nor at the very back.
Example 7 Solution: First, let the 6 boys line up, which can be done in $A_{6}^{6}$ different ways; then let the 4 girls line up, which can be done in $A_{4}^{4}$ different ways; finally, insert the entire line of girls between two boys, which can be done in 5 different ways. Therefore, there are a total of $5 \cdot A_{6}^{6} \cdot A_{4}^{4}=5! \cdot 6!$ different ways for the group to line up and walk.