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Unformatted text preview: X = 36 | X < 38) = P( X = 36) .46
P( X < 38) .76 Copyright © 2002 by College Entrance Examination Board. All rights reserved.
Advanced Placement Program and AP are registered trademarks of the College Entrance Examination Board. 5 AP® STATISTICS
2002 SCORING GUIDELINES (Form B)
Question 2 (cont’d.)
Part (a) is
Essentially correct if computes P(X ≤ 38) (except for minor arithmetic errors)
Partially correct if computes P(X = 38) = 0.16 or P(X > 38) = .08 or P(X < 38) = 0.76 or
P ( X ³ 38) = 0.24 or gives 0.92 but does not show any work.
Incorrect if no calculation or nonsensical calculation (e.g., 0.921 , 36.9
= 0.927 ,
= 0.971 ) or
38 only pure expected value calculations.
Part (b) is
Essentially correct if (except for minor arithmetic errors) correctly computes expected value for
number of no shows and indicates fully where the 36.9 and 4.1 come from.
Rounding this value to 4 is considered a minus, though can be forgiven with “about” or
Partially correct if correctly computes expected value of X = number of
passengers who show up for the flight (instead of no shows) and shows work,
OR if incorrectly computes the first expected value but “subtracts,”
OR if correctly computes the first expected value b...
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