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:

Jamie is a window cleaner who was tired after cleaning the windows on the 45th floor and thus leaped inside the building.

Solution:

In the corners of the square, tighten two ropes. Tighten another rope between them by putting rings on each rope. That rope should be tightened on the sheep's neck on the other end.

Solution:

The probability of two numbers being relatively prime is 60%. Thus if you keep playing the bet, you will hypothetically make 20 cents on every play.

Thus, you should accept the bet.

Solution:

The bridge won't break.

When the car has travelled half of the bridge, that is 15km, the car must have used more than 300 grams of fuel. Therefore, the impact of bird's added weight will be zero literally.

Solution:

Hockey Stick $49.50 & ball $0.50

Solution:

If you see the picture, they formed a pentagonal shape and achieved the required.

Solution:

The woman told him to take out one nut each from the rest of the wheels and use them.

Solution:

10,15,9,20,12

Explanation:
The score obtained on the first throw is 10.
The score obtained on the second throw is 15.
The score obtained on the third throw is 9.
The score obtained on the fourth throw is 20.
The score obtained on the fifth throw is 12.

Solution:

The Winchester brothers - sam and dean

Solution:

It can be done in 8 moves as shown in the animated image below.