Homework Help: AP Statistics

Posted by Laura on Sunday, January 3, 2010 at 4:41pm.

Of all U.S. fourth graders, 71% are assigned mathematics homework three or more times per week. If 5 fouth graders are randomly selected to be checked for this frequency of homework assignment during a randomly chosen week, find the probability that
A.) exactly one fourth grader was assigned homework three or more times that week
B.) no fourth grader was assigned homework three or more times that week
C.) at least one fourth grader was assigned homework three or more tiems that week

AP Statistics - bobpursley, Sunday, January 3, 2010 at 4:49pm
a)

NNNNY
NNNYN
NNYNN
NYNNN
YNNNN
so, there are five ways to sort the fourth graders
Pr(one)=5*.71*.29^4=.0251 check that.
b)Pr(none)=.29^5
c) Pr(at least one)=1-Pr(none)
AP Statistics - sally, Friday, January 13, 2012 at 11:18am
A. .0251
B. .0020
C. None

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