Question 164160
The maximum value for sin ax is 1 
the minimum value for sin ax is -1


so the answers:
1. the maximum value for y = 1/3 sin 5x is 
            1/3 * 1 = 1/3 (a)


2. the minimum value for g(x) = 4sin 5x + k is
            4*(-1) + k 
           = -4 + k
           = k - 4 (d)