In a class Mohan is at the 15 th position from top and 50 th from the bottom. How many total students are there in the class ?

Mohan is counted in both positions, so the two numbers overlap by one student. Add them and subtract 1: 15 + 50 - 1 = 64.

Check it directly. Being 15th from the top means 14 students are ahead of him. Being 50th from the bottom means 49 students are behind him. Total = 14 + 1 (Mohan) + 49 = 64, which is option B.

• A) 65 is what you get by simply adding 15 + 50 and forgetting that Mohan is counted twice.
• C) 66 and D) 67 come from adding an extra one or two students that the data does not support.

Core concept: position-from-both-ends problems. Always split the total as (students ahead) + (self) + (students behind). This kind of ranking logic appears in UPPSC's reasoning and CSAT-style questions, and it mirrors how merit positions are read in service rank lists.

Trap: adding the two positions and stopping there, which gives 65.