The flow in a river can be modeled as a log$-$normal distribution. From the data, it was estimated that, the probability that the flow exceeds $1,194$ cfs is $50\%$ and the probability that it exceeds $100$ cfs is $90\%.$ Let X denote the flow in cfs in the river. Flood conditions occur when flow is $5000$ cfs or above. To compute the percentage of time flood conditions occur for this river, we have to find, P$($X$>=5000)=1-$P$($Z