If you have two arms,you have more arms than world's average
Yes, this is true.
But it does not mean half of the population in this world has only one arm. The fact lies in the realm of Mathematics.
Let's imagine a small town of 2,000 people.
Now let's say one of them only has one arm.
So the total number of arms is 3,999.
The average number of arms per person is:
|number of arms||=||3,999||=||1.9995|
|number of people||2,000|
So 2 is above average!
We can now see that 1,999 of the people in our small town have an above average number of arms. They have 2 arms and the average is 1.9995.