Notice that the sequence has a common ratio of 4:
[tex]\begin{gathered} 15\times4=60 \\ 60\times4=240 \end{gathered}[/tex]The n-th term of a sequence with first term equal to a and common ratio r is:
[tex]a\cdot r^{n-1}[/tex]The first term of this sequence is 15 and the common ratio is 4, then the nth term is:
[tex]15\cdot4^{n-1}[/tex]Substitute n=6 to find the 6th term:
[tex]15\cdot4^{6-1}=15\cdot4^5=15\cdot1024=15,360[/tex]Therefore, the 6th term of the sequence, is:
[tex]15,360[/tex]