Kishan is the son-in-law of Rajesh's father-in-law. Rajesh's wife has a younger sister. Based on this information, how is Rajesh related to Kishan?

Introduction / Context:
This is a relation puzzle about in-laws. We are told that Kishan is the son-in-law of Rajesh's father-in-law and that Rajesh's wife has a younger sister. You must track who Rajesh's father-in-law is, whom his daughters are and how Kishan fits into that family, then express Rajesh's relation to Kishan using a standard term like brother-in-law.

Given Data / Assumptions:

• Rajesh has a wife, so Rajesh is male.
• Rajesh's father-in-law is the father of Rajesh's wife.
• Kishan is the son-in-law of Rajesh's father-in-law, so Kishan is married to one of the daughters of Rajesh's father-in-law.
• Rajesh's wife has a younger sister, so the father-in-law has at least two daughters: Rajesh's wife and her younger sister.
• We assume the usual scenario that Kishan is married to this younger sister, making him another son-in-law of the same father-in-law.

Concept / Approach:
Rajesh is married to one daughter of the father-in-law. Kishan, as the son-in-law of the same man, is married to another daughter, most naturally the younger sister of Rajesh's wife given in the statement. Thus, Rajesh and Kishan are husbands of two sisters. Husbands of two sisters are called brothers-in-law to each other. Therefore, Rajesh is related to Kishan as a brother-in-law.

Step-by-Step Solution:
Step 1: Let F be Rajesh's father-in-law. F has at least two daughters: the elder daughter W (Rajesh's wife) and a younger sister S.Step 2: Rajesh is married to W, so he is one son-in-law of F.Step 3: Kishan is given as the son-in-law of F, so Kishan is married to one of F's daughters.Step 4: Because F has exactly these two daughters in the context, the natural and intended reading is that Kishan is married to S, the younger sister of Rajesh's wife.Step 5: Rajesh and Kishan are therefore husbands of two sisters (W and S).Step 6: Husbands of two sisters are brothers-in-law to each other.

Verification / Alternative check:
Construct a family tree: F has two daughters W and S. W marries Rajesh; S marries Kishan. Rajesh sees Kishan as the husband of his sister-in-law S. Conversely, Kishan sees Rajesh as the husband of his wife's sister W. In both directions, the relation is brother-in-law. There is no supporting information to make Rajesh Kishan's brother, father or cousin; all the data point to marriage into the same family by two daughters.

Why Other Options Are Wrong:
Brother would require Rajesh and Kishan to share parents, which is never stated.Father is impossible because Kishan is described as a son-in-law of Rajesh's father-in-law, putting him in the same generation as Rajesh, not the next.Cousin would imply that they share grandparents through their parents rather than being related through marriage.Uncle would mean one is a sibling of a parent of the other, which is not the case here.

Common Pitfalls:
Some students misinterpret father-in-law and son-in-law relations and end up thinking Kishan is married to Rajesh's daughter instead of his wife's sister. Another frequent mistake is forgetting that both Rajesh and Kishan are sons-in-law of the same man and that the natural connection between them, given the presence of a younger sister for Rajesh's wife, is that they marry the two sisters. Keeping track of who marries whom is crucial.

Final Answer:
Rajesh is related to Kishan as his Brother-in-law.