Basic Terms of Probability

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Basic Terms of Probability
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Objectives

• Determine the probability of a given event .
• Determine the odds of a given event.
• Use a Punnet square to determine probability.

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Vocabulary

• experiment
• sample space - the set S of all possible
  outcomes of an experiment
• event any subset E of the sample space S
• probability success divided by total
• odds success to failures

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Formulas
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A jar on your desk contains twelve black, eight
red, ten yellow, and five green jellybeans.  You
pick a jellybean without looking.
What is the probability that the jellybean is
green?
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A jar on your desk contains twelve black, eight
red, ten yellow, and five green jellybeans.  You
pick a jellybean without looking.
What is the probability that the jellybean is
not yellow?
7
A jar on your desk contains twelve black, eight
red, ten yellow, and five green jellybeans.  You
pick a jellybean without looking.
What are the odds in favor of picking a black
jellybean?
8
A card is drawn from a well-shuffled deck of 52
cards.
What is the probability that the card is a heart?
9
A card is drawn from a well-shuffled deck of 52
cards.
What are the odds of drawing a heart?
10
A card is drawn from a well-shuffled deck of 52
cards.
What is the probability that the card is below a
9 (ace high)?
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A card is drawn from a well-shuffled deck of 52
cards.
What are the odds of a card below a 9 (ace high)?
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A family has three children.  Using b to stand
for boy and g to stand for girl, and using
ordered triples such as(bbg) give
the sample space
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A family has three children.  Using b to stand
for boy and g to stand for girl, and using
ordered triples such as(b, b, g) give
the event E that the family has exactly two
daughters
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A family has three children.  Using b to stand
for boy and g to stand for girl, and using
ordered triples such as(b, b, g) give
the event F that the family has at least two
daughters
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A family has three children.  Using b to stand
for boy and g to stand for girl, and using
ordered triples such as(b, b, g) give
the event G that the family has three daughters
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Vocabulary

• dominant
• recessive
• Punnett square
• codominant

17
Mendel found that snapdragons have no color
dominance a snapdragon with one red gene and one
white gene will have pink flowers.  If a pure-red
snapdragon is crossed with a pure-white
snapdragon, find the probability of the
following.

• a red offspring
• a white offspring
• a pink offspring

18
If carrier-detection tests show that two
prospective parents have sickle cell trait (and
are therefore carriers), find the probability of
each of the following

• their child would have sickle cell anemia.
• their child would have sickle cell trait.
• their child would be healthy (free of symptoms).

19
Tay-Sachs disease is a recessive disease. If
carrier-detection tests show that one prospective
parent is a carrier of Tay-Sachs and the other
has no Tay-Sachs gene, find the probability of
each of the following.

• their child would have the disease.
• their child would be a carrier.
• their child would be healthy (free of symptoms)