2008, Form B, Question 5 · 4 points
Two trains meeting on a single track
Find the distribution of the difference in two independent normal travel times, the long-run share of days one train waits, and the delay that cuts that chance to 0.01.
This exam had six free-response questions, each scored from 0 to 4. Its Question 6, the Investigative Task, is no longer part of the exam. The current exam has 4 free-response questions in 90 minutes. The skills these questions practice still count.
Not in the current course. All three parts use the distribution of a difference of two independent random variables, which relies on combining random variables, and the current course no longer includes that.
Lessons this question draws on
1 Read the question
The question is College Board's, from the 2008, Form B exam. It starts on page 9 of the PDF. College Board no longer posts this exam, so it opens from the copy of College Board's PDF that the Internet Archive saved on April 27, 2025.
2 Write your answer
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Scoring guidelines (PDF, page 15)
Question, scoring guidelines and Chief Reader report: College Board, from the Internet Archive. The title and summary are ours.