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Correct Answer : C
Explanation:
Same direction : relative speed is s1-s2 Opposite Direction: relative speed is : s1+s2 S1= l/4 S2=l/5 Same direction: time= distance/speed =2l/s1-s2; Substitute s1 and s2 values in above equation, we get 40 seconds But no option contains this answer. Assuming that given question is for opposite direction then we get answer as 4.44 sec. So choose 4.44 seconds as answer