Answer:
5
Explanation:
Number of habitable planets = 1000
Fraction of planet with life = 1/10
Fraction of planet with life and civilization (before) = 1/4
Fraction of planet with life and civilization (now) =1/5
Therefore multiplying we have:
1000×1/10×1/4×1/5 = 5
Answer:
4 Ohms
Explanation
(This is seriously not as hard as it looks :)
You only need two types of calculations:
- replace two resistances, say, R1 and R2, connected in a series by a single one R. In this case the new R is a sum of the two:

- replace two resistances that are connected in parallel. In that case:

I am attaching a drawing showing the process of stepwise replacement of two resistances at a time (am using rectangles to represent a resistance). The left-most image shows the starting point, just a little bit "warped" to see it better. The two resistances (6 Ohm next to each other) are in parallel and are replaced by a single resistance (3 Ohm, see formula above) in the top middle image. Next, the two resistances (9 and 3 Ohm) are nicely in series, so they can be replaced by their sum, which is what happened going to the top right image. Finally we have two resistances in parallel and they can be replaced by a single, final, resistance as shown in the bottom right image. That (4 Ohms) is the <em>equivalent resistance</em> of the original circuit.
Using these two transformations you will be able to solve step by step any problem like this, no matter how complex.
Adding an intermediate switch is not an attractive choice to span the distance between two switches due to expense issues. It may have different ports.
<h3>What is a network switch?</h3>
A switch refers to a hardware tool capable of connecting different computer devices in a network.
A network switch can connect devices on a network by centralizing communications among many devices in a given local area network.
A switch may support different speeds for transmission of data (for example, one gigabit Gbps per second).
Learn more about network switches here:
brainly.com/question/12811608
A because water has more volume when it's warmer
Newton's second law of motion states the following:

In which

is the force,

is the mass, and

is the acceleration of the object.
So, the answer is B.