Question: In a "keep-fit" gymnasium class there are fifteen females enrolled in a weight-loss program. They all have been grouped in any one of the five weight-groups W1, W2, W3, W4, or W5. One instructor is assigned to one weight-group only. Sonali, Shalini, Shubhra, and Shahira belong to the same weight-group. Sonali and Rupa are in one weight-group, Rupali and Renuka are also in one weight-group. Rupa, Radha, Renuka, Ruchika and Ritu belong to different weight-groups. Somya cannot be with Ritu, and Tara cannot be with Radha. Komal cannot be with Radha, Somya, or Ritu. Shahira is in W1 and Somya is in W4 with Ruchika. Sweta and Jyotika cannot be with Rupali, but are in a weight-group with total membership of four. No weight-group can have more than five or less than one member. Amita, Babita, Chandrika, Deepika, and Elina are instructors of weight-groups with membership sizes 5, 4, 3, 2 and 1, respectively. Who is the instructor of Radha?
Explanation:
Based on the information provided, the data can be summarized as follows.
From the first two statements, we get that Sonali, Shalini, Shubhra, Shahira and Rupa are in the same weight group with a group size of 5.
It is given that Rupa, Radha, Renuka, Ruchika and Ritu belong to different weight-groups.
∴ There are 4 groups (i.e. of Radha, Renuka, Ruchika and Ritu) remaining.
∴ In the group along with Ruchika and Somya, there cannot be Radha, Renuka and Ritu, thus forming a group of 2.
Also, Komal cannot be with Radha, Ritu and Somya (Ruchika) and Rupa.
∴ She has go with Rupali and Renuka, thus forming a group of size 3.
If W1, W2, W3, W4 and W5 represent weight groups in the descending order of the group size then Sweta and Jyotika must contain Ritu and Tara as their group members as Somya and Ruchika belong to W4 thus forming a group of 4.
Otherwise Sweta and Jyotika can be either with Ritu and Tara or with Somya and Ruchika, but in both the cases Radha is alone and doesnot have any other member in the group.
∴ Elina is the instructor of Radha.
Hence, option (b)