Description for Correct answer:
Rate downstream = \( \Large \frac{55}{\frac{5}{2}} \)

= \( \Large \frac{55 \times 2 }{5} = 22 kmph \)

Time taken in upstream journey

= \( \Large (\frac{5}{2} \times 2.2) hours \)

= 5.5 hours

\( \Large \therefore Rate upstream = \frac{55}{5.5} \)

= 10 kmph

\( \Large \therefore \) Speed of boat in still water

= \( \Large \frac{1}{2} (22 + 10) \)

= \( \Large \frac{1}{2} \times 32 = 16 \ kmph \)