4. A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series: 68, 72, 65, 69, 62, 66, _?__
6. A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series. 6, 18, 54, ? , 486, 1458
7. A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series. 1, 0.125, 1/27, 1/64, ? , 1/216