Solution:

First stack of cards = 11
Second stack of cards = 7
Third stack of cards = 6

First move:
First stack of cards = 11 - 7 = 4
Second stack of cards = 7 + 7 = 14
Third stack of cards = 6

Second move:
First stack of cards = 4
Second stack of cards = 14 - 6 = 8
Third stack of cards = 6 + 6 = 12

Third Move:
First stack of cards = 4 + 4 = 8
Second stack of cards = 8
Third stack of cards = 12 - 4 = 8

Solution:

The girl was born on 29 February. Thus her birthday came once in four years only while her sister was born on a normal day and celebrated her birthday every year. Thus the girl had a chance of depositing money only 10 times in 4 years through which she collected $2500 while her sister took $50 from the piggy bank every year making the total amount to be $2000. Thus when the piggy bank was opened, it had just $500.

Solution:

There are three roses and four bees.

Solution:

The clerk said that every day the password is CHANGED. Changed is the password.

Solution:

step 3 is wrong

Solution:

If you ask the guard who always tells the truth, he would tell you the other guard would point you to the door of death. If you ask the guard who always lies, he would tell you the opposite door of the truth-telling guard and point you to the door of death. In either case, both guards will point to the door of death so you should choose the other one.

Solution:

2003.

Explanation:
Its a series of prime numbes.

Solution:

See the colored sticks in the picture. We have moved those sticks in the position given in the second image corresponding with the color.

Solution:

She is near the trunk of the tree as shown below.

Solution:

Shikhar hit a sixer and then got retired hurt.
Suresh Raina came but he got run out after he and Kohli had crossed halfway.
On the next ball, Kohli scored a six and was not out at 100.

Solution:

To do it, the marbles must be arranged as the vertices of an octahedron. If you are unsure, check the image below.