Probability - Geometric Sequence Problem

I have been trying to solve a problem which states the following:

For every hour less than 8, an initial value depreciates by 7.9%. The initial value given is 87. This is what I have calculated so far:

8 hours = 87

7 hours = 80.127

6 hours = 73.797

5 hours = 67.967

4 hours = 62.598

3 hours = 57.652

2 hours = 53.098

1 hours = 48.903

From the above, it can be seen that the problem is a geometric sequence, having a constant ratio of 0.921.

The problem asks to find the number of hours it would take to reach 50. I know that multiplying a previous value by 0.921 gives you the next value for a whole hour (bottom to top). However, I am really struggling to find a way to calculate the hours for the value 50. How can I go about doing this?

I have been trying to solve a problem which states the following:

For every hour less than 8, an initial value depreciates by 7.9%. The initial value given is 87. This is what I have calculated so far:

8 hours = 87

7 hours = 80.127

6 hours = 73.797

5 hours = 67.967

4 hours = 62.598

3 hours = 57.652

2 hours = 53.098

1 hours = 48.903

From the above, it can be seen that the problem is a geometric sequence, having a constant ratio of 0.921.

The problem asks to find the number of hours it would take to reach 50. I know that multiplying a previous value by 0.921 gives you the next value for a whole hour (bottom to top). However, I am really struggling to find a way to calculate the hours for the value 50. How can I go about doing this?