Correct Answer - Option 1 : 47 min

**Given:**

A monkey has to climb a pole of a height of 50 m.

It can climb 4 m in 1st minute and comes down 2m in 2nd minute.

This process will be repeated till the monkey reaches the top.

Concept used:

If the height of the pole is z meter and if a monkey climbs x meter in first min and y meter in second min and the process will be repeated till the monkey reaches the top,

then we have to calculate first the required time in which it will climb (z - x) meter.

And to climb at the top, total time the monkey will take {the required time in which it will climb (z - x) meter + 1}

Calculation:

Monkey climbs in 1st min = 4 m

Monkey comes down in 2nd min = 2 m

That means, monkey climbs effectively in 2 min = 4 – 2 = 2 m

This process repeated till (2 × 23) min

Monkey climbs till 46 min = 2 × 23 = 46 m

Now, in 47th min monkey again climb 4 m

So, Monkey climbs till 47 min = 46 + 4 = 50 m

**∴ In 47 min monkey will climb a pole of 50 m.**