A safety manager wanted to determine the probability of having a lost workday charged to a worker because of a back injury. The safety manager determined that for the 87 claims of all types reported in one year, 18 involved lost workdays. Of the 87 reported claims, 23 were for back injuries, and of these 23 cases, 14 resulted in lost workdays. The safety manager wishes to determine the probability of a lost workday case if the case was the result of a back injury.