Demand is Normally distributed with mean of 28 per week and a weekly variance of 9. The ordering cost is $36.41. Lead time is 4 weeks. Shortages cost an estimated $1.84 per unit short to expedite orders to appease customers. The holding cost is $9.33 per week. What is the critical rato if the target service level is 0.8. (Enter a number with two decimal places, e.g. 0.12).