Ms. Jonna is told that 30% of students have at least
one class that uses a free online textbook (OER),70% of students
are concerned about the cost of books, and 17% of students have at
least one class that uses a free online book AND are concerned
about the cost of books.
a) create a contingency table with the above information
b) Determine the likehood that a student is concerned about the
cost of books given that they have at least one class that uses a
free online book.
c) Are the events of having at least one class that uses a free
online book and being concerned about the cost of books
independent? Briefly explain
Ans:
a)
P(free online textbook)=0.30
P(concerned about cost of books)=0.70
P(free online textbook and concerned about cost)=0.17
b)P(concerned about cost/free online textbook)
=P(free online textbook and concerned about cost)/P(free online textbook)
=0.17/0.30
=0.567
c)For two events A and B to be independent:
P(A and B)=P(A)*P(B)
But
P(free online textbook and concerned about cost)=0.17
P(free online textbook)*P(concerned about cost of books)=0.30*0.70=0.21
As,both are not equal so,both events are not independent.
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