A man who can swim 48 meter/minute in still water swims 200 meter against the current and 200 meter with the current. If the difference between these two times is 10 minutes, then what is the speed of the current?

Correct option is D

Let the speed of current be nm/min and speed of man in still water be 4m/min.
So speed of man with the current be n + 48 m/min and speed of man against the current be (45 - x) m/min
time = Distance/Speed
for 200m against current taken time = 200/(48−x) min
for 200m with current taken time = 200/(48+x) min
Given Difference b/w time is 10 min
= 200[1/48−x − 1/48+x]=10
=$$20[(48+x−48+x) / (48)^2−x^2]=1$$​
= $$20 (2x) = 48^2 - x^2$$​
= $$x^2 + 40x - 2304 = 0$$​
= $$x^2 + 72x - 32x - 2304 = 0$$​
=$$x(x + 72) - 32(x - 72) = 0$$​
= $$(x - 32)(x + 72) = 0$$​
$$x = 72 (Not possible), x = 32$$​