Solution:

.05

Given the equation 8/x = 160, when you solve for x, you indeed get:

8/x = 160

To find x, you can simply invert the fraction:
x/8 = 1/160

Now, to isolate x, multiply both sides by 8:
x = 8 * (1/160)
x = 8/160
x = 1/20 = 0.05

Solution:

Six.

There are only five colors, so six socks guarantee that two will be the same color.

Solution:

It can be solved as below.

Solution:

What must be kept in mind before you start calculating through any method is that the weights can be put on both the pans.

So the weights - 1, 3, 7, 12, 43, 76, 102

The oldest man that can be weighed using these weights is a man aged 122 years

Solution:

Sam : 2
Dean : 5
Castiel : 7

Age diff
7 - 2 = '5' is prime
7 - 5 = '2' is prime
5 - 2 = '3' is prime

Solution:

They used the planks in the manner that is shown in the figure.

Solution:

Move and then pour all juice from second glass to fifth glass.

Solution:

Put one black rock in one sack and put all the rest in the other one. In such manner you will get about 3/4 probability of surviving.

Solution:

fIvE thOUsAnd(5000)

Solution:

Everyone will done one day or other.

Abraham Lincoln era is too old and we expect most of them(if not all) to be dead by now.

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.