If Joshua finds that the number of phones sold according to his function \( p(n) = 400(1.7)^n \) is too high, he needs to adjust the coefficient in front of the function.
The coefficient of 400 represents the initial number of phones sold when there are 0 locations, and increasing it would result in an even higher number of phones sold. Therefore, to make the function reflect a lower number of phones sold, he should:
C. Decrease the coefficient that is currently 400.
This will yield a lower initial value and thereby reduce the total number of phones sold.