CONDITIONAL PROBABILITY
(Worksheet)
1.
A die is rolled. Determine the probability that the number is a 5 given that it is
greater than 3.
2.
Determine the probability of rolling a sum of seven with two dice if it is known that
the first die rolled was a 3.
3.
A card is drawn from a standard deck. Determine the probability that it is a jack given
that it is a face card.
4.
A die is thrown twice. Determine the probability that the sum of the rolls is less than
four given that:
a)
5.
b)
the first roll is a 1.
In a family of four, Rob and Lisa are the parents and Michael and Jonathan are the
children. Each family member has three presents under the Christmas tree.
Determine the probability that a selected present is for:
a)
b)
6.
one of the rolls is a 1;
Jonathan, given that the present if for a male;
Lisa, if it is known that the present is for one of the parents.
After a recent Canadian census it was discovered that among all of the families in
Canada, 40% have no children, 25% have 1 child, 18% have 2 children, 10% have 3
children, 5% have 4 children, and 2% have 5 or more children. If a Canadian family is
selected at random, determine the probability that the family:
a)
b)
has more than 2 children;
has more than 2 children given that it has at least 1 child.
7.
In an election for the president of the student council, it is estimated that Anne has a
40% chance of winning, Tanya has a 30% chance, Graham has a 20% chance, and
Maria has a 10% chance. Just before the election, Graham withdraws. Determine the
adjusted chances of winning for Anne, Tanya, and Maria.
8.
Complete question #9 on page 335 in the textbook.
ANSWERSANSWERSANSWERS
1
3
1
b)
2
1.
2.
1
6
6.a)
1
3
17
b)
60
3.
17
100
3
1
b)
11
3
1 3 1
7. , ,
2 8 8
4.a)
5.a)
1
3