Solution:

It can be done in four steps as shown below

1. Man, take the goat with him, leave the goat at the other end and come back alone.
2. Man, take the lion with him, leave the Lion and come back with the goat
3. Man, take the grass with him and come back alone.
4. The man takes the goat with him.

Solution:

They are not playing against each other.

Solution:

89

Solution:

6 members.
Let's say 'C' is for crew and 'M' is Michael.

So their formation at that time is like:

C
C
C
M - 4th from back and front.
C
C
C

Solution:

It's a clever trick teaser.
We should note that Christmas occurs after 51 weeks and 2 days as in a calendar year new year comes before Christmas.

Solution:

The timer of a microwave.

The timer of a microwave generally consists of 4 digits. First two digit for minutes and next two for seconds.
So,
99 indicates - 1 minute 39 seconds
100 indicates - 1 minutes (1:00)

Solution:

The fastest or even the slowest rabbit can only run till the mid point into the given garden. After the mid point, it will actually be running out of the given garden.

Solution:

It is an easy task. You just have to give the last chocolate along with the basket. That way, all gets a chocolate and the last one remains in the basket as well.

Solution:

You should reject the bet. When you give him $100, he won't be able to convert it into $500 dollar and will lose the bet. Thus, he'll give you $50. But your $100 will be with him and therefore, you are going to lose your money anyhow

Solution:

Alexandra used two planks as shown in the picture below.