[tex]a_5=ra_4=r^2a_3=r^3a_2=r^4a_1\iff150.06=16r^4\implies r\approx\pm1.75[/tex]
Regardless of the sign of the common ratio, then, you will have
[tex]a_{17}=r^{16}a_1\approx16(\pm1.75)^{16}\approx123802.31[/tex]
The actual term would be closer to [tex]123794[/tex] if you didn't have to round.
