I think a reason/scenario for not changing the original array should be given so we know why not to change it. I did forget to account for negative numbers too, so I agree with both statements.

Thanks for all comments.

I updated description.

Good that you added a specification of the approximation to the description. I tried it before that and ended up implementing a solution based on infinite series. My solution was more exact, but failed because you assumed an approximation.

Btw, ellipse is spelled with two 'l's.

It passed the tests. Which is enough for me :)

Test cases should be updated to
a) check that the original array is not mutated (as per the description)
b) pass in some negative numbers (as the description explicitly says that only positive numbers should be summed)