Multiple choice

A boat takes half time in moving a certain distance downstream than upstream. The ratio of the speed of the boat in still water and that of the current is एक नाव एक निश्चित दूरी को अनुप्रवाह तय करने में ऊर्ध्वप्रवाह की तुलना में आधा समय लेती है | स्थिर जल में नाव की चाल का धारा की चाल से अनुपात है

  1. 2 : 1

  2. 1 : 2

  3. 4 : 3

  4. 3 : 1
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let boat speed = b, current speed = c. Downstream: b+c, upstream: b-c. Time ratio upstream:downstream = 2:1, so speed ratio (downstream:upstream) = 2:1. Thus (b+c)/(b-c) = 2/1, giving b+c = 2b-2c, so b = 3c, or b:c = 3:1. Verification: If b=3, c=1, downstream=4, upstream=2, time ratio = 1:2 ✓

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