Transcript Risky Business

Risky Business
Probability Unit
Cobb County Humane Society is making
a new ID tag number system. Animal
ID’s will consist of 2 letters followed by
4 numbers. How many possible animal
IDs can there be?
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Q – How many IDs?
L and L and N and N and N and N
Strategy - Multiply
26 possible letter outcomes and 10 possible
number outcomes
26 * 26 * 10 * 10 * 10 * 10
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Answer – 6,760,000 IDs
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Based on the information above,
what is the probability that Mrs.
Aller’s dog, Peanut, will be assigned
the ID number BZ2738?
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I am looking for a probability, so I know my answer
must be between 0 and 1.
1 out of 6,760,000 or 1/6,760,000
I have 4 dice that have 3 sides. Each die
has the numbers 1-3. (Yes they look
strange, but we will say they are “fair”.)
What is the probability that all 4 dice
will roll a 2?
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Q – P(2) and P(2) and P(2) and P(2)
Strategy – Multiply
3 possible outcomes for each die (1,2,3)
Probability of 1 of them rolling a 2 is 1/3
So, 1/3 * 1/3 * 1/3 * 1/3 =
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Answer = 1/81
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Macy’s Junior department has a wide
selection of dresses for the upcoming
homecoming dance season. They have 6
sizes, 8 styles, and 5 different fabrics
from which to choose. How many
different dresses does Macy’s have
available?
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Q – I am looking for the number of dress combinations.
Strategy – Multiply (Counting Principle)
6 sizes * 8 styles * 5 fabrics =
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Answer = 240 dresses
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If X and Y are independent events
such that P(X) = 0.36 and P(Y) =
0.15, what is the probability that
either X or Y will occur?
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Question – P(X) or P(Y)
Strategy – add
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0.36 + 0.15 =
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Answer = 0.51 or 51%
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If X and Y are independent events
such that P(X) = 0.36 and P(Y) =
0.15, what is the probability that
both X and Y will occur?
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Question – P(X) and P(Y)
Strategy – Multiply
0.36 * 0.15 =
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Answer = 0.0540 or 5.4%
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Boots has in her toy box 4 chew toys, 3 bones, 1 ball, 3
pigs ears, and 1 shedding brush. She also has in her
cookie jar 6 beef, 8 chicken, and 2 vegetable flavored
cookies. Assuming Boots can reach into each container
and randomly pick just one item from each container,
what is the probability that Boots will select a chew toy
from the toy box and a chicken flavored cookie from the
cookie jar?
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Q – P(chew toy from toy box) and P(chicken from cookie jar)
Strategy – Multiply
P(chew toy) = 4/12 or 1/3, P(chicken) = 8/16 or ½
(note they have different sample spaces)
So, 4/12 * 8/16 = 1/3 * ½ =
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Answer = 1/6
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Jazmine has 3 pairs of sandals, 5
pairs of tennis shoes, and 8 pairs of
dress shoes. How many choices of
shoes does Jazmine have?
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Q – How many pairs of shoes does Jazmine have? –
NOT how many types of shoe.
Strategy – add up all of her shoes.
3 sandals + 5 tennis + 8 dress =
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Answer = 16 pairs of shoes
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The concession stand at the football game sells
hamburgers, hot dogs and chicken sandwiches. They
also sell skittles, and air heads. Their drink offerings
are coke, sprite, and water. Make a tree diagram
showing all the possible combinations of meat,
candy, and drink meals someone can order.
Of the students at Awtrey today,
5/6 are wearing jeans, and 1/3 are
wearing a hoodie. What is P(jeans
and hoodie)?
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Question – P(jeans) and P(hoodie)
Strategy – Multiply
5/6 * 1/3 =
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Answer = 5/18
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Bonus Round
Based on the information in the previous
question, what is P(jeans or hoodie)?
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Q – P(jeans) or P(hoodie) – BUT I must
subtract everyone wearing both
Strategy – add then subtract both jeans &
hoodie
Since I am adding, I need to get common
denominators
5/6 + 2/6 = 7/6 – 5/18 = 21/18 – 5/18 =
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Answer = 16/18 or 8/9
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