HSC - উচ্চতর গণিত ২য় পত্র→অধ্যায়-০৯ঃ সরলরেখায় বা সমতলে চলমান কণার গতি→All Topics

$\text { A man takes } 8 \mathrm{~min} \text { to cross a } 400 \mathrm{~m} \text { wide river by swimming, if there is no current in the river. However, he }$$\text { takes } 10 \text { minutes to cross the river, if there is current in the river. The velocity of the current is- }$