Solution:

First climb the first rope and carry the end of the second one with you. Now cut the first rope and flush with the ceiling, then swing down on the second. This time, climb up the second and cut that flush with the ceiling as well but only part way till it can withstand your weight. Now slowly climb down till you're just short of the bottom. Now tie a tiny loop at this portion and climb up some two feet. Then secure the loop about your feet and jump to the ground. With a three feet fall, you won't be hurt but the force will snap off the rope at top and you will have the whole rope with you.

Solution:

You will know what to do by looking at the picture. This was fun right? Now go ask your friends to do it.

Solution:

There can be many ways to get the job done. You can begin with a diagonal move. We are moving the 1st to the 4th place. After that, move 6 to 1, 2 to 6, 5 to 2 and 4 to 5. And you are done.
You can start with moving 6 to 3 as well. There are many other possibilities. Go figure out for yourself.

Solution:

The best way to analyze the situation would be forcing a win for white when the black player plays anywhere but a corner square. Refer to the given figure for the current positions. Now, if black plays 7 to block the white player from having three in a row, white will move 5 to 6 and will win. But since you get to place only three markers, black can place the marker at 6 and white won't be able to add one more at 7 to win. And moving the 9 marker to 7 will take two steps.

But white can still get to square 7 before black is able to block him or form a three in a row. In this manner, no matter what black does, the white player can always win the game if he begins from the center square.

Solution:

The iron brick will make the water level higher.

Explanation:
But on the contrary, in actual terms, none of them will help in rising the water. They will actually drop the water level. This is because, they have a large effect on the water level while in the boat but when they are dropped into the water. They will drop the water level. Iron brick being the lighter one will drop the water level less because it will have less effect on the water from the boat but will displace the equal amount of water as the gold when it is dropped into the water. Thus it can be said that it will make the water level higher.

Solution:

You can easily understand what we did through the given figure. But if somehow, you are unable to understand, here is what we did. We just cut along the lines as shown. Remove the red parts from the square. Tilt it a bit and then place the cut portions as shown in the figure.

Solution:

When he took the first bite of the salmon, he realized that what he ate at the island was not salmon but his friend

Solution:

There are sixty marks in the given figure, thus it is safe to assume that each mark represents a minute.

Now, the hour hand is on a mark when the minute hand is on [0, 12, 24, 36, 48]. When the minute hand is on a mark, the second hand is on noon. But the orange hand cannot be the second hand. (It would be onnoon and it would be eighteen minutes past/before a full hour.)

a) Purple is on 12. Green indicates twenty four minutes. orange indicates forty two [minutes] = 8 + 2/5 [hours] = 8:24
b) Purple is on 12. Green indicates thirty six minutes. orange indicates eighteen [minutes] = 3 + 3/5 [hours] = 3:36
c) Green is on 12 = 3:36
d) Green is on 12 = 8:24.

Please note that the watch could be rotated upside down as well.

Solution:

You must be aware of the fact that the standard weighing system is Imperial system. This is how we weigh things or ourselves and thus the warning must be for 130 pounds according to the Imperial system.

But gold is weighed in the Troy system. In Troy system, 12 ounces makes one pound whereas in Imperial system, 16 ounces make one pound.

Thus 40 pounds (20+20) of gold bars will be 30 pounds in imperial system. The weight of thief is 100 pounds. Thus, the total is 130 pounds which can be accommodated on the rope and thus he was able to cross safely.

Solution:

It is not as tough as it seems. The strategy is quite simple. You just have to pick up a card out of first three whenever you find a 9 or higher number.

Let us offer you a strong valid reason for the strategy. The probability that the four card kept below are below the number nine is 32*31*30*29 / 52*51*50*49 = 0.133
Thus in such case, you will lose $2 to $9 with equal probability = 0.133/8 = 0.0166

Let us now calculate the probability that one of the four cards is nine or even higher.
1 – 0.133 = 0.867
Now you will surely stop at the first sight of 9 or any value above 9 as per the strategy. Thus you have a chance of winning -1, 0, 1, 2, 3 with an equal probability = 0.867/5 = 0.173

In such case you stand a chance of winning overall amount of 0.14 every game you play.

Let us consider the other strategies. If you want to stop at the sight of 10 or above 10, the expected amount you will win per game will be 0.09 which is way below the present strategy. If you want to stop at above ten only, you will have an expected winning in negative.