Correct Answer - Option 2 : 12

**Given:**

Ratio of speed of boat A, boat B and stream = 15 : 14 : 10

Speed of boat A – Speed of boat B = 2 kmph

**Concept used:**

Time = Distance/Speed

**Calculation:**

Difference of boat A and boat B = 15 – 14 = 1

1 unit equal to 2 kmph

So, speed of boat A is 30 kmph

speed of boat B is 28 kmph

speed of stream is 20 kmph

Time taken by boat A = [150/(30 + 20)]

⇒ 150/50

⇒ 3 hours

Time taken by boat B = [120/(28 - 20)]

⇒ 120/8

⇒ 15 hours

Diffrence between time taken by boat A and boat B

⇒ 15 – 3

⇒ 12 hours

**∴**** The difference between time taken by boat A and boat B is 12 hours.**