Consider (1)

Indicates that when A covers 7 blocks, B covers 2 blocks, this is sufficient to say where they will intersect again.

So (1) is sufficient.

Consider (2)

This does not give any information about their relative speeds and is not sufficient.

ANS â€“ (1) Alone is sufficient.

Cheers,

Anand

kevincan wrote:

The above rectangle is a channel that in broken into 8 identical square sectors. Boats A and B are at opposite ends of the channel. They begin sailing at the same time, and go back and forth parallel to the shores from one end of the channel to the other. Neither boat varies its speed at any time and the time each boat spends turning around is negligible. In which sector will they pass each other for the second time?

(1) They pass for the first time in sector 7.

(2) They pass for the third time in sector 3.