How does the time taken for backpropagation change with the increase in neurons? This is a question I come across a lot in interviews but I don't understand how and what the answer is:-
If we have a neural net, and we double the neurons in it, how does the time taken for backpropagation change? does it increase by

2 times
4 times
8 times
16 times
The general idea is that time complexity is related to the number of operations needed to perform all the steps of backpropagation. You can find an example workthrough here:
https://medium.com/swlh/computational-complexity-of-neural-networks-38c01e7e566a
For a 4 layer NN it seems the complexity is O(n⁵), where n is the number of nodes of each layer (also n is the same for every layer in that example).