This is very similar to the last question:-
0.51No = No e^_0.0001t
t = ln 0.51 / 0.0001
= 6733 years
When a function is reflected, it must be reflected over a line
The new function is: 
The equation is given as:

The rule of reflection over the y-axis is:

So, we have:

Rewrite as:

Hence, the new function is:

Read more about reflections at:
brainly.com/question/938117