Description for Correct answer:
Speed of boat in still water = x kmph

Speed of current = y kmph

\( \Large \therefore \) Rate downstream

= (x + y) kmph

Rate upstream = (x - y) kmph

\( \Large \therefore \frac{y}{x + y} = \frac{1}{7} \)

=> 7y = x + y

=> x = 6y

Again, \( \Large \frac{2.75}{x - y} = \frac{11}{60} \)

=> \( \Large 11 (x - y) = 2.75 \times 60 = 165 \)

=> \( \Large x - y = \frac{165}{11} = 15 \)

=> 6y - y = 15

=> 5y = 15

=> y = 3 kmph

\( \Large \therefore x = 6 \times 3 = 18 kmph \)

\( \Large \therefore \) x + y = Rate downstream

= 18 + 3 = 21 kmph

Distance between points A and B

= \( \Large \ Rate \ downstream \times \ Time \)

= \( \Large \frac{21 \times 52}{60} = 18.2 \ km \)