An ant climbing up a vertical pole ascends 12 meters and slips down 5 meters in every alternate hour. If the pole is 63 meters high how long will it take it to reach the top?

Since it climbs 7 meter in every 2 hr. At the end of 14 hours it would have climbed up to 49 mt. In 15th hour it will reach 61 mt. Then drops back to 56 mt in the 16th hour. It will take another 35 min to travel remaining 7 mt since it will be ascending in the 17th hour. Thus, 16 hr and 35 min.

Detail Explanation:
Given,
Ant ascends 12 meters in first hours and slips down 5 meters in second hour.
This is repeated in every alternate hour.
It means in every two hours Ant ascends (12 - 5 = 7 meters)

Therefore, in ends of 14 hours,
Ant ascends = $$\frac{{14 \times 7}}{2}$$  = 49 meters.
So, In next hour i.e 15 hour, Ant will ascends another 12 meter.
Till end of 15^th hour, Ant climbed = 49 + 12 = 61 meters. But in 16^th hour, Ant will slips down 5 meters (61 - 5 = 56 meters).
Remaining pole to climb,
= 63 - 56
= 7