Homework 04

Homework 04 - 
 Homework
Assignment
4
...

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Unformatted text preview: 
 Homework
Assignment
4
 Psychology
60
 Spring
2010
 
 
 
 General
Instructions:
 ‐ Make
sure
your
homework
has
written
on
it:
 o YOUR
NAME
 o YOUR
STUDENT
ID
 o YOUR
TA’S
NAME
(you
can
find
this
on
the
syllabus)
 
 ‐ Please
be
sure
your
homework
answers
are
LEGIBLE.
 
 ‐ For
homework
problems
requiring
calculation,
you
must
show
all
of
your
work,
including
 intermediate
steps,
in
order
to
receive
credit.


 ‐ Please
circle
final
answers
to
problems
that
require
computation;
doing
this
will
make
sure
 we
can
find
your
final
answer.

 ‐ For
questions
requiring
a
short
written
answer,
be
as
concise
as
possible
while
still
 explaining
your
answer.

 
 ‐ If
you
have
questions
about
concepts,
feel
free
to
post
questions
on
the
class
discussion
 board.
You
may
also
email
your
TAs,
but
do
so
only
after
you
have
looked
through
the
book
 for
an
answer
to
your
question.

 ‐ Homework
is
due
at
the
start
of
class
on
Tuesday
(by
11:15).
No
late
homework
will
be
 accepted.
 
 
 
 1) For
a
population
with
μ
=
50,
and
σ
=
10,
find
the
standard
error,
 σ X ,
when:

 a. n
=
4
 b. n
=
25
 c. n
=
100

 
 2) The
distribution
of
sample
means
is
not
always
distributed
normally.
Under
what
 circumstances
will
the
distribution
of
sample
means
not
be
normal?
 
 3) For
a
population
with
σ
=
20:
 a. How
large
a
sample
would
be
needed
to
have
a
standard
error
less
than
10
points?
 b. How
large
a
sample
would
be
needed
to
have
a
standard
error
less
than
4
points?
 c. How
large
a
sample
would
be
needed
to
have
a
standard
error
less
than
2
points?
 
 4) A
population
has
a
mean
of
μ
=
100
and
a
standard
deviation
of
σ
=
20.
Find
the
z‐score
for
 each
of
the
following
sample
means
obtained
from
this
population:
 a. X =
102
for
sample
of
4
scores
 b. X =
102
for
sample
of
100
scores
 5) 6) 7) 8) 
 
 c. X =
95
for
sample
of
16
scores
 d. X =
95
for
sample
of
25
scores
 
 A
random
sample
is
obtained
from
a
population
with
a
mean
of
μ
=
50
and
a
standard
 deviation
σ
=
12.
 a. For
a
sample
of
n
=
4
scores,
would
a
sample
mean
of
 X =
55
be
considered
an
 unlikely
sample
mean
or
a
fairly
typical
sample
mean?

Explain.

 b. For
a
sample
of
n
=
36
scores,
would
a
sample
mean
of
 X =
55
be
considered
an
 unlikely
sample
mean
or
a
fairly
typical
sample
mean?

Explain.

 
 A
random
sample
is
obtained
from
a
normal
population
with
a
mean
of
μ
=
80
and
a
standard
 deviation
of
σ
=
8.
Which
of
the
following
outcomes
is
more
likely:
A
sample
mean
greater
 than X 
=
86
for
a
sample
of
n
=
4
scores,
or
a
sample
mean
greater
than
 X =
84
for
a
sample
 of
n
=
16
scores.
Explain
and
defend
your
answer.
 
 For
a
normal
distribution
with
μ
=
50
and
σ
=
8:
 a. What
proportion
of
scores
in
the
population
have
values
between
46
and
54?
 b. What
proportion
of
samples
of
size
n
=
4
from
this
population
will
have
sample
means
 between
46
and
54?
 c. What
proportion
of
samples
of
size
n
=
16
from
this
population
will
have
sample
 means
between
46
and
54? 
 The
average
age
for
licensed
drivers
in
the
US
is
μ
=
42.6
years
old
with
a
standard
deviation
 σ
=
12.
The
distribution
is
approximately
normal.
 a. A
researcher
obtained
a
sample
of
n
=
36
drivers
who
received
parking
tickets.
The
 average
age
for
these
drivers
was X 
=
41.7.

Is
this
sample
mean
unlikely
to
occur
by
 chance
alone
or
is
it
a
fairly
typical
sample
mean
with
a
sample
of
n
=
36
from
this
 population?

 b. 
The
same
researcher
obtained
a
sample
of
n
=
16
drivers
who
received
speeding
 tickets.
The
average
age
for
these
drivers
was X 
=
34.4.

Is
this
sample
mean
unlikely
 to
occur
by
chance
alone
or
is
it
a
fairly
typical
sample
mean
with
a
sample
of
n
=
16
 from
this
population?

 ...
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