# STAT 2000 Lecture Notes - Lecture 13: Wii Fit, Random Variable

February 17, 2017

• Example 8: Wii Fit Study

o std. dev. 15 mean=111

▪

→ z-score

▪ percentile: enter mean=0, std. dev.=1;

o enter mean=111, std. dev.=15;

▪ 116.7799 corresponds to the 65th percentile

6.3 Probabilities When Observation Has Two Possible Outcomes

• 0= has type O blood; N=do not have type O blood

• P(O)=0.45; P(N)=0.55

Person 1

Person 2

Person 3

# w/ Type O

Blood

Probability

O

O

O

3

0.45*0.45*0.45=0.0911

O

O

N

2

0.45*0.45*0.55=

O

N

O

2

SAME

N

O

O

2

SAME

N

N

O

1

0.55*0.55*0.45=

N

O

N

1

SAME

O

N

N

1

SAME

N

N

N

0

0.55*0.55*0.55=0.1664

• 8 possibilities → 2*2*2=8

•

•

X

0

1

2

3

P(x)

0.1664

0.4084

0.3341

0.0911

• Using the binomial calculator

o n trials that has two possible outcomes → outcome of interest is called a success

and other outcome is called a failure

o each trial has saem probability of success denoted by p; probability of failure

denoted by q (1-p)

o each variable is independent

• Notation for binomial experiment

o n= # of trials

o p= probability of success for any given trials

o q= probability of failure for any given trial (q=1-p)

o x=# of successes for n trials

o n and p are the parameters of the binomial random variable

• Example 10: Drinking and Driving

o n=15 p=1/5=0.20

o

o

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