BPSC – Combined Competitive Examination · প্রশ্ন 90
A 140 m long train runs at 60 km/h and a dog runs parallel in the same direction at 18 km/h. The train will pass the dog in:
উত্তর দেখান ও ব্যাখ্যা
উত্তর: (B) 12 seconds
ব্যাখ্যা
Same direction: relative speed = 60 − 18 = 42 km/h = 11.67 m/s; time = 140/11.67 = 12 s.
- (A) ভুল
Wrong: incorrect.
- (B) সঠিক
Correct: relative speed 42 km/h = 35/3 m/s; 140 ÷ 35/3 = 12 s.
- (C) ভুল
Wrong: incorrect.
- (D) ভুল
Wrong: incorrect.
- (E) ভুল
Wrong: only one of the options A–D is correct.