STAT 225 Quiz 4A+++++

STAT 225 Quiz 4


A recent survey indicated that 48% of mobile devices are iPhones. To see if this seemed to be true of
Purdue's campus, you randomly ask 10 people if they use an iPhone. Assume all individuals on campus are
independent, let Y be the number of people asked that use an iPhone.
1. What are the distribution and parameter(s) of Y ? 3 points
2. What is the probability exactly 6 of the people asked use an iPhone? 5 points
3. Given no more than 8 people surveyed use an iPhone, what is the probability exactly 6 people asked
use an iPhone? 7 points
Binomial(n,p)
P(B = b) =
􀀀n
b

pb(1 􀀀 p)n􀀀b
E[B] = np
V ar(B) = np(1 􀀀 p)
Hypergeometric(N,n,p=m
N )
P(H = h) =
􀀀m
h
􀀀N􀀀m
n􀀀h

􀀀N
n

E[H] = nm
N
V ar(H) = N􀀀n
N􀀀1 np(1 􀀀 p)
Poisson()
P(X = x) = e􀀀x
x!
E[X] =
V ar(X) =
STAT 225 Quiz 4
October 4, 2013
NAME:
Directions: You have 10 minutes to complete the quiz. You are allowed a calculator as speci ed in the
syllabus. If necessary, round decimal answers to 4 signi cant digits. Show all work to receive full credit.
Instructors will not interpret questions for you.
A recent survey indicated that 46% of mobile devices are iPhones. To see if this seemed to be true of
Purdue's campus, you randomly ask 10 people if they use an iPhone. Assume all individuals on campus are
independent, let Y be the number of people asked that use an iPhone.
1. What are the distribution and parameter(s) of Y ? 3 points
2. What is the probability exactly 7 of the people asked use an iPhone? 5 points
3. Given no more than 8 people surveyed use an iPhone, what is the probability exactly 7 people asked
use an iPhone? 7 points
Binomial(n,p)
P(B = b) =
􀀀n
b

pb(1 􀀀 p)n􀀀b
E[B] = np
V ar(B) = np(1 􀀀 p)
Hypergeometric(N,n,p=m
N )
P(H = h) =
􀀀m
h
􀀀N􀀀m
n􀀀h

􀀀N
n

E[H] = nm
N
V ar(H) = N􀀀n
N􀀀1 np(1 􀀀 p)
Poisson()
P(X = x) = e􀀀x
x!
E[X] =
V ar(X) =
STAT 225 Quiz 4
October 4, 2013
NAME:
Directions: You have 10 minutes to complete the quiz. You are allowed a calculator as speci ed in the
syllabus. If necessary, round decimal answers to 4 signi cant digits. Show all work to receive full credit.
Instructors will not interpret questions for you.
A recent survey indicated that 52% of mobile devices are iPhones. To see if this seemed to be true of
Purdue's campus, you randomly ask 10 people if they use an iPhone. Assume all individuals on campus are
independent, let Y be the number of people asked that use an iPhone.
1. What are the distribution and parameter(s) of Y ? 3 points
2. What is the probability exactly 4 of the people asked use an iPhone? 5 points
3. Given no more than 8 people surveyed use an iPhone, what is the probability exactly 4 people asked
use an iPhone? 7 points
Binomial(n,p)
P(B = b) =
􀀀n
b

pb(1 􀀀 p)n􀀀b
E[B] = np
V ar(B) = np(1 􀀀 p)
Hypergeometric(N,n,p=m
N )
P(H = h) =
􀀀m
h
􀀀N􀀀m
n􀀀h

􀀀N
n

E[H] = nm
N
V ar(H) = N􀀀n
N􀀀1 np(1 􀀀 p)
Poisson()
P(X = x) = e􀀀x
x!
E[X] =
V ar(X) =
STAT 225 Quiz 4
October 4, 2013
NAME:
Directions: You have 10 minutes to complete the quiz. You are allowed a calculator as speci ed in the
syllabus. If necessary, round decimal answers to 4 signi cant digits. Show all work to receive full credit.
Instructors will not interpret questions for you.
A recent survey in the Exponent indicated that 42% of mobile devices are iPhones. You randomly ask 10
people on Purdue's campus if they use an iPhone. Assume all individuals on campus are independent, let Y
be the number of people asked that use an iPhone.
1. What are the distribution and parameter(s) of Y ? 3 points
2. What is the probability exactly 5 of the people asked use an iPhone? 5 points
3. Given no more than 8 people surveyed use an iPhone, what is the probability exactly 5 people asked
use an iPhone? 7 points
Binomial(n,p)
P(B = b) =
􀀀n
b

pb(1 􀀀 p)n􀀀b
E[B] = np
V ar(B) = np(1 􀀀 p)
Hypergeometric(N,n,p=m
N )
P(H = h) =
􀀀m
h
􀀀N􀀀m
n􀀀h

􀀀N
n

E[H] = nm
N
V ar(H) = N􀀀n
N􀀀1 np(1 􀀀 p)
Poisson()
P(X = x) = e􀀀x
x!
E[X] =
V ar(X) =