 In such situation, the following expression can be employed: where  RA is the ratio of the native-to-labeled fish in the lake , RB is the ratio of the native-to-labeled fish in the lot of nB marked fish which are added to the pond, and RAB is the ratio of the native-to-labeled fish captured during the second visit.
<meaning-changed>  In such situation, the following expression can be employed: where  RA is the ratio of the native-to-labeled fish in the lake , RB is the ratio of the native-to-labeled fish in the lot of nB marked fish which are added to the pond, and RAB is the ratio of the native-to-labeled fish captured during the second visit.
 In such situation, the following expression can be employed: where , as indicated above, nA and nB represent the number of fish in the lake and the number of fish added to the lake, respectively; RA is the ratio of the native-to-labeled fish in the lake , RB is the ratio of the native-to-labeled fish in the lot of nB marked fish which are added to the pond, and RAB is the ratio of the native-to-labeled fish captured during the second visit.