the value of r of the geometric series n=11.3(0.8)n-1

General formula for nth term of any geometric series is 
Here 'r' is the common ratio
a_1 is the first term of the series
Now we compare the given formula with general formula
Compare
with 
The value of r= 0.8
Rounded would be $13.89.
0.07 * 12.98 = 0.9086 and add that to 12.89 :)
18 is 10 players
19 is 94-70=24 the range is 24