Solution:

This is because the queue for buying a donut is extremely long due to which the car engine becomes cool and gives trouble. While the queue for buying brownie is pretty small and thus the car gives no trouble at all.

Solution:

The number is 37.

The missing guess can be either 24 or 50 and the missing difference is 8.

Solution:

This puzzle is quite similar to the cheating husbands puzzle. The same logic applies here.

After the announcement, if there is only one person with green eyes, he will observe everyone and will come to the conclusion that he himself has green eyes.

If two persons have green eyes, they will see everyone and find out that there is one person with green eyes. So they will expect him to leave. But if no one leaves on that day, on the next day both of them will understand that they both have green eyes and will leave the island.

Thus if you keep going like this or apply the rules of induction, you will find that since there are 100 green eyed people on that island, all of them will leave the island on the 100th day after the announcement.

Solution:

I had 10 candies in the beginning.

Explanation:
Let us take and solve this problem in the reverse direction.

At the end, I was left with 1 candy. Let me take the extra one candy back from my younger son. Now since I gave him half of what I had, we must be having the same number of candies. I have 2, which means he also have 2. This implies that I was left with 4 candies after I gave some to the elder son.

Let me take back the extra candy from my elder son now. Now I have 5 candies. Since I gave him half of what I had, he must be having 5 candies as well. Thus, I had 10 candies in the beginning.

Solution:

It is a lateral thinking puzzle and thus it's not about anything logical.

The man who walked in the movie theater was once a father of twin brothers. Despite of the fact that they were twins, their nature was starkly opposite. While David was quite peaceful and generous, Robin was very rude and violent.

On a certain day, David came running to the man and told him that Robin had killed a man. The man rushed to the crime scene with his son and saw that the man was dead with Robin near the body. He started fighting with Robin and accidentally killed him. The police arrested the man and he was sent to prison for ten years. While in his first month at the prison, he received a letter from his son which said that he was not interested in meeting him ever and that he can't forgive his father for what he did to his brother.

After ten years, he was released and came out of the prison only to know that his son was now a small time movie star and his latest movie was running in a nearby theater. While watching the movie, he smiled when he saw his son David on screen. But the next moment, the camera shifted on his arm where he saw a birthmark that belonged to Robin. He realized that on that day the one who came to him was not David but Robin and he actually killed David.

Filled with a grief and shock he decided to take his own life. He would have never forgiven himself for what he did to his son David.

Solution:

When fifteen minutes have passed, the hour hand has already moved exactly one fourth of an hour. Thus the angle between the hour hand and minute hand will be of 7.5 degrees.

Solution:

12 minutes

Explanation:
Yes, surely they can all make it out of the cave.

First, father and mother will go. Time taken = 2 minutes.
Father comes back. Time taken = 2 + 1 = 3 minutes.
Both children go. Time taken = 3 + 5 = 8 minutes.
Mother comes back. Time taken = 8 + 2 = 10 minutes.
Mother and Father go. Time taken = 10 + 2 = 12 minutes.

Thus in 12 minutes, all of them will be out of the cave through the tunnel.

Solution:

Just form an equilateral triangle, planting trees at the vertices. Now find the center of the triangle and plant the fourth three on that point. In this manner you will form a shape of tetrahedron and all the trees will have equal distance between each other.

Solution:

If you look into the picture, you can see the cut lines. If the four people cut along with the lines, each one of them will have 1/5th of the cake.

Solution:

The first figure tells you where you have to make the cut in the paper. Now you have two pieces of paper. If you rotate the right piece to 180 degrees, you will get what is shown in the figure two. Now the hole is in the center of the paper.