PrepTest 127 · Section 3 · Question 13

The Chalk Arrow Code

At summer camp, the big scavenger hunt was on. Every camper carried chalk and drew arrows on the sidewalk as they walked. Nadia noticed something. Arrows from a prize spot back to the cabin were drawn thick and dark. Arrows from trips that found nothing were thin and faint. 'Aha,' said Nadia. 'The campers are sharing where the prizes are with the whole cabin!' Owen tilted his head. 'Maybe. But a message only counts if somebody reads it. What if nobody pays attention to how thick an arrow is?' Priya nodded. 'Right. If we learned that campers looking for prizes usually follow the thick arrows instead of the thin ones, then Nadia's idea gets much stronger. Then the arrows are doing real work.'

During the scavenger hunt, campers leave chalk arrows along their paths. Arrows on paths from a prize back to the cabin are drawn thicker than arrows on paths that found nothing. So the campers apparently share information about prize locations with the rest of the cabin.

Which one of these, if true, gives the most help to Nadia's argument?

The Case of the Flashlight Signals

A lighthouse keeper claimed the fishing crews used flashlight blinks to share where the fish were. Mr. Whitfield represented the keeper in a dispute over credit. 'Your Honor, boats coming home with a full catch blink three times. Boats that found nothing blink once. Clearly they are telling the others!' Judge Mae Tanaka frowned. 'Mr. Whitfield, a signal is only a message if someone reads it. Do other boats steer toward the three-blink boats?' Mr. Whitfield grinned and handed up a logbook. 'They do, Your Honor. Hungry crews head for triple blinks far more often than single ones.' The judge nodded. 'Now that is evidence of sharing.'