please help

28 days 0/13 A bakery sells an average of 48 chocolate chip cookies each day, with a standard deviation of 11 cookies. The manager of the bakery wants to make sure that they are selling as many cookies as possible each day, so she wants to identify days when their sales are in the bottom 15% of the sampling distribution. Use Excel to find how many cookies must be sold each day to put the bakery in the bottom 15% if the manager analyzes 30 days of sales. Round a and of down to the nearest whole number. Provide your answer below: 0- = cookies