UGC NET Questions (Paper – 1)

A is correct because with downstream speed (b + s) and upstream speed (b − s), their average is b, the still-water speed. B is correct as the stream’s speed is half the difference of downstream and upstream speeds. D is true because if stream speed is zero, upstream and downstream speeds coincide, and E applies the standard time = distance ÷ speed relation used in these problems. C is false because upstream travel is slower and hence takes more time than downstream for the same distance. Therefore, A, B, D and E only are correct.

Option A:
Option A lists A, B and D but omits E, failing to mention the basic time formula that underlies most calculations in these problems. Because it does not include all true statements, it is incomplete.

Option B:
Option B is correct as it groups all true statements and excludes C, which reverses the comparison of upstream and downstream times. It reflects how relative speed, still-water speed and stream speed are handled in aptitude questions.

Option C:
Option C wrongly includes C, which claims upstream time is always less, and omits A, failing to describe the average-speed relationship. Including C makes this option logically incorrect.

Option D:
Option D includes C as well, and therefore it too inherits the error that contradicts basic time–speed relationships, despite including some correct statements. Hence it cannot be the right answer.