Answer:
50 degrees =0.873 radian
Formula 50 degrees x π/180= 0.8727 radians
The rule of a geometric sequence:

We have:

Find 
substitute:

Solution: We are given below data:

Now to find the mean deviation, we use the below formula:

Where:
represents the summation
X, represents the observation.
represents the mean
N represents the number of observation.


Therefore, the mean deviation is:

= 4