Multiple choice

Speed of a boat in still water is 9 kmph, and the speed of stream is 3 km per hour. Find the time taken by the boat to go 7.8 km upstream.

  1. 1 hour 15 minutes

  2. 1 hour 18 minutes

  3. 1 hour 12 minutes

  4. 1 hour 6 minutes

  5. 1 hour 10 minutes
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The upstream speed is the boat speed minus the stream speed, which is 9 - 3 = 6 kmph. Time equals distance divided by speed, so 7.8 / 6 = 1.3 hours. 0.3 hours is 0.3 * 60 = 18 minutes, resulting in 1 hour 18 minutes.

AI explanation

The upstream speed of the boat is calculated by subtracting the stream speed from the still water speed, giving 9 minus 3 equals 6 kmph. Using the formula time equals distance divided by speed, the time taken is 7.8 divided by 6, which equals 1.3 hours. To convert 0.3 hours into minutes, multiply by 60 to get 18 minutes, making the total time 1 hour 18 minutes.

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