AP CSA FRQ Guide
2010 FRQ 3: Trail
Analyze trail elevation data to determine whether a segment is level and whether the whole trail is difficult.
Array Analysis22 minute targetarraysmin/maxMath.absloops
Skills Tested
What this FRQ is really practicing
arraysmin/maxMath.absloops
Treat these skills as the study checklist. If any tag feels shaky, review that topic before attempting the full written response.
Starter Approach
How to begin without copying a solution
- 1For a segment, find the minimum and maximum elevations from start through end inclusive.
- 2For the whole trail, count adjacent changes whose absolute value is at least 30.
Write a first attempt before revealing any solution outline. Most AP CSA FRQ progress comes from tracing your own code and finding the missing case.
Common Mistakes
Mistakes to watch for while writing
Using only the first and last marker for levelness.
Ignoring downhill changes when checking difficulty.
Using > 30 instead of at least 30.
Self Check
Review questions before you submit
Loops through the segment inclusively.
The end marker is part of the segment.
Tracks both minimum and maximum values.
A segment is level based on max minus min.
Uses absolute adjacent elevation changes.
Both uphill and downhill changes count.
Returns true only when at least three large changes occur.
The archive prompt threshold is a count of changes.
Practice Links