What is 0.0002 percent of 400 - step by step solution

To get the solution, we are looking for, we need to point out what we know.

1. We assume, that the number 400 is 100% - because it's the output value of the task.
2. We assume, that x is the value we are looking for.
3. If 400 is 100%, so we can write it down as 400=100%.
4. We know, that x is 0.0002% of the output value, so we can write it down as x=0.0002%.
5. Now we have two simple equations:
1) 400=100%
2) x=0.0002%
where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:
400/x=100%/0.0002%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.

7. Solution for what is 0.0002% of 400

400/x=100/0.0002
(400/x)*x=(100/0.0002)*x       - we multiply both sides of the equation by x
400=500000*x       - we divide both sides of the equation by (500000) to get x
400/500000=x
0.0008=x
x=0.0008

now we have:
0.0002% of 400=0.0008