Multiple choice

In a fixed time, a boy swims double the distance along the current that he swims against the current. If the speed of the current is 3 km/hr, the speed of the boy in still water is एक निश्चित समय में, एक लड़का धारा के अनुदिश धारा के विरुद्ध दोगुनी दूरी तय करती है | यदि धारा की चाल 3 किमी./घंटा है, स्थिर जल में लड़के की चाल है

  1. 6 km/hr./किमी./घंटा

  2. 9 km/hr./किमी./घंटा

  3. 10 km/hr./किमी./घंटा

  4. 12 km/hr./किमी./घंटा
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In fixed time t, distance downstream = (v+3)t, distance upstream = (v-3)t. Given: (v+3)t = 2(v-3)t, so v+3 = 2v-6, v = 9. Downstream distance = 12t, upstream = 6t. Ratio is 2:1 as stated. Speed in still water is 9 km/hr.

Keep practicing — related questions