A monkey ascends a greased pole 12 metres high. He ascends 2 metres in first minute and slips down 1 metre in the alternate minute. In which minute, he reaches the top ?  Choose the correct choice from the following.
A) 21st	B) 22nd	C) 23rd	D) 24th	E) None of these
In 2 minutes, he ascends = 1 metre   ∴ 10 metres, he ascends in 20 minutes.   ∴ He reaches the top in 21st minute.   Answer 22nd
<result>B</result>
A monkey ascends a greased pole 12 metres high. He ascends 2 metres in first minute and slips down 1 metre in the alternate minute. In which minute, he reaches the top ?