Solution:

yaM

Explanation:
voN luJ ? raM beF

Step-1: Reversing the input text gives us:
Feb Mar ? Jul Nov

Step-2: Replace by month numbers
2 3 ? 7 11

Step-3: Find the relation
They all are prime numbers, the missing number here is "5".

Step-4:
5th month is May and reverse of May is yaM (answer)

Solution:

Since the door is not visible in this picture, the bus is moving in the left direction.

Solution:

Steps:
1) Light fire on first bar from both the ends and second bar from one end.

2) After 30 seconds(when first bar gets completely burned out) , burn the second bar from second end as well.

3) When second run completely gets burned , you know its 45 seconds.

Solution:

36 meters.

100/v1 = 80/v2
100/v2 = 80/v3

20+(20/v2)*v3=20+16 = 36

Solution:

Old password : altered

New Password : distinct

Solution:

Kid1, he was left with one rock.

Solution:

"World War I" was named after after "World War II"

Solution:

The mules is moving in circular path and hence outside legs travels more distance than inner legs.

Solution:

A cigar stuck in the wall

Solution:

The three errors are as follows:
a) fynd is spelled wrong. The correct spelling is 'find'.
b) that is not appropriate to use here. It should be 'this'.
c) There are only two errors in the question and that is the third error because the questions asks us to find three.

Solution:

2100 miles.

Each vowel equivalent to 500 and each consonant equivalent to -200