Jan Tuttle Is the Inventory Manager of an Art Supply

Jan Tuttle is the inventory manager of an art supply store.She uses a periodic review system for all oil paints.The number of periods between orders (P) for red #68 is 15 workdays.(The store operates 50 weeks per year,five workdays per week. ) Additional information concerning red #68 follows. Demand = 30 units/workday
Standard deviation of daily demand = 4 units/workday
Lead-time = 7 workdays
Desired cycle-service level = 85%
A normal distribution table is appended to this exam.
What is the target inventory level T for red #68?

A) less than or equal to 550 units
B) greater than 550 but less than or equal to 600 units
C) greater than 600 but less than or equal to 650 units
D) greater than 650 units