Stat 121 - Exam 3
Ho: p = po
1 sample z for proportions
Ha: p (>,<, not equal to po)
Suppose a standard spray will Because 120(0.10) = 12 > 10 and 120(0.90) = 108 > 10
be used in an orchard unless
the supervisor can show that
the proportion of infected trees
is less than 10%, in which case
a cheaper, less effective spray
will be used. 120 trees will be
randomly sampled. Should the
cheaper spray be used? Why
was the sampling distribution
of p approximately Normal
assuming p=0.10? ^ a.
Because n = 120 > 30.
b. Because 120(0.10) = 12 > 10 and
120(0.90) =
108 > 10 c. Since 10 trees are
infected, p
=0.0833 and 120(0.0833) = 10 ≥
20 and
120(0.91667) = 110 > 10.
,Do good smells bring good experiment—can conclude causation
business? A study was
conducted at a small pizza
restaurant in France on
Saturday evenings in May. On
one evening a relaxing
lavender odor was spread
through the restaurant; on
another, a stimulating lemon
odor; and a third evening had
no odor. Treatments were
randomly assigned to days. On
each evening the time (in
minutes) customers stayed in
the restaurant was recorded.
Is this an experiment or an
observational study? Can we
conclude causation? a.
experiment—can conclude
causation b. experiment—
cannot conclude causation c.
observational study—can
conclude causation d.
observational study—cannot
conclude causation
Do good smells bring good Time spent in restaurant—quantitative
business? A study was
conducted at a small pizza
restaurant in France on
Saturday evenings in May. On
one evening a relaxing
lavender odor was spread
through the restaurant; on
another, a stimulating lemon
odor; and a third evening had
no odor. Treatments were
randomly assigned to days. On
each evening the time (in
minutes) customers stayed in
the restaurant was recorded.
What is the response
variable? What type of
variable?
Do good smells bring good Type of odor—categorical
business? A study was
conducted at a small pizza
, restaurant in France on
Saturday evenings in May. On
one evening a relaxing
lavender odor was spread
through the restaurant; on
another, a stimulating lemon
odor; and a third evening had
no odor. Treatments were
randomly assigned to days. On
each evening the time (in
minutes) customers stayed in
the restaurant was recorded.
What is the explanatory
variable? What type of
variable?
Do good smells bring good All customers
business? A study was
conducted at a small pizza
restaurant in France on
Saturday evenings in May. On
one evening a relaxing
lavender odor was spread
through the restaurant; on
another, a stimulating lemon
odor; and a third evening had
no odor. Treatments were
randomly assigned to days. On
each evening the time (in
minutes) customers stayed in
the restaurant was recorded.
What is the population of
interest?
a. all customers b. all times
spent in restaurant c. all
evenings d. all restaurants
Ho: p = po
1 sample z for proportions
Ha: p (>,<, not equal to po)
Suppose a standard spray will Because 120(0.10) = 12 > 10 and 120(0.90) = 108 > 10
be used in an orchard unless
the supervisor can show that
the proportion of infected trees
is less than 10%, in which case
a cheaper, less effective spray
will be used. 120 trees will be
randomly sampled. Should the
cheaper spray be used? Why
was the sampling distribution
of p approximately Normal
assuming p=0.10? ^ a.
Because n = 120 > 30.
b. Because 120(0.10) = 12 > 10 and
120(0.90) =
108 > 10 c. Since 10 trees are
infected, p
=0.0833 and 120(0.0833) = 10 ≥
20 and
120(0.91667) = 110 > 10.
,Do good smells bring good experiment—can conclude causation
business? A study was
conducted at a small pizza
restaurant in France on
Saturday evenings in May. On
one evening a relaxing
lavender odor was spread
through the restaurant; on
another, a stimulating lemon
odor; and a third evening had
no odor. Treatments were
randomly assigned to days. On
each evening the time (in
minutes) customers stayed in
the restaurant was recorded.
Is this an experiment or an
observational study? Can we
conclude causation? a.
experiment—can conclude
causation b. experiment—
cannot conclude causation c.
observational study—can
conclude causation d.
observational study—cannot
conclude causation
Do good smells bring good Time spent in restaurant—quantitative
business? A study was
conducted at a small pizza
restaurant in France on
Saturday evenings in May. On
one evening a relaxing
lavender odor was spread
through the restaurant; on
another, a stimulating lemon
odor; and a third evening had
no odor. Treatments were
randomly assigned to days. On
each evening the time (in
minutes) customers stayed in
the restaurant was recorded.
What is the response
variable? What type of
variable?
Do good smells bring good Type of odor—categorical
business? A study was
conducted at a small pizza
, restaurant in France on
Saturday evenings in May. On
one evening a relaxing
lavender odor was spread
through the restaurant; on
another, a stimulating lemon
odor; and a third evening had
no odor. Treatments were
randomly assigned to days. On
each evening the time (in
minutes) customers stayed in
the restaurant was recorded.
What is the explanatory
variable? What type of
variable?
Do good smells bring good All customers
business? A study was
conducted at a small pizza
restaurant in France on
Saturday evenings in May. On
one evening a relaxing
lavender odor was spread
through the restaurant; on
another, a stimulating lemon
odor; and a third evening had
no odor. Treatments were
randomly assigned to days. On
each evening the time (in
minutes) customers stayed in
the restaurant was recorded.
What is the population of
interest?
a. all customers b. all times
spent in restaurant c. all
evenings d. all restaurants
