Correct Answer - Option 2 :

\(21\frac{2}{3}\;sec\)
**Given:**

Distance travelled by boat = 130 metre

Speed of stream = 6 m/s

**Concept used:**

If the speed of boat in still water is ‘x’ km/hr and speed of stream is ‘y’ km/hr, then:

Upstream speed = Speed of boat - Speed of stream = (x – y)

Downstream speed = Speed of boat + Speed of stream = (x + y)

**Calculations:**

Let the speed of boats be 5x and 3x

∴ For faster boat

Downstream speed = Speed of boat + Speed of stream = 5x + 6

⇒ 5x + 6 = (130/5) = 26

⇒ 5x = 20

⇒ x = 4

∴ Speed of Faster boat = 5 × 4 = 20 km/hr

Speed of slower boat = 3 × 4 = 12 km/hr

∴ Time taken by the slower boat to cover 130 m upstream

⇒ Time = Distance/Speed

⇒ Time = 130/(12 – 6)

⇒ Time = 65/3

∴ Time taken by the slower boat = 65/3 \( = 21\frac{2}{3}\)