Description for Correct answer:
On first minute monkey climbs 1 meter.
On second minute it slips 1 / 2 meter.
For every two minute it climbs 1 / 2 meter.

So Average speed = 1 meter / 4 minutes
For 11 meters, time taken = 44 minutes.

For last 1 meter jump add 1 minute.
So time taken = 45 minutes.