Statistics 511-6, Quiz 4
1. A random sample of 10 houses in Big Rapids, each of which is heated with natural
gas, is selected and the amount of gas (therms) used during the month of January is
determined for each house. The resultin
Examples for chapter 3
A store carries flash drives with either 1 GB, 2 GB, 4 GB, 8 GB, or 16
GB of memory. The accompanying table gives the distribution of Y =
the amount of memory in a purchased drive:
Let X = the number of days of sick leave taken by
A statistical hypothesis, or just hypothesis, is a claim or assertion
about population characteristic
The null hypothesis, denoted by H0, is the claim that is initially
assumed to be true (the prior belief claim). The alternative
Practice Exam 2
1. The breaking strength of a rivet has a mean value of 10,000 psi and a standard deviation of 500 psi.
(a) What is the probability that the sample mean breaking strength for a random sample of 40 rivets is
between 9950 and 10,250?
Midterm Examination 2
Tuesday, November 12th, 2015
Name (please print) :_
Time: 60 minutes
Please sign below to indicate your agreement with the following honor code.
Honor code: I promise not to cheat on this exam. I will n
Suppose that the parameter of interest is a population mean and that
1. The population distribution is normal;
2. The value of the population standard deviation is known.
This provides a random interval that contains the populati
The Two-Sample t Test and Confidence Interval
When the population distribution are both normal, the standardized
has approximately a t distribution with df v estimated
from the data by
The Two-Sample t Test and Confide
1. The following data specify scores of an exam for students in a class.
A frequency table is provided below.
60 under 65
Example 1 Consider an experiment in which several different types of
shipping boxes were compared with respect to compression strength
i = 1, I is a group index
xi, j = the jth measurement taken from the ith population,
1. The number of space shuttle flights taken by each of 313 astronauts are
summarized in the following frequency distribution.
Example 15 Suppose we want to find the flaw ratio p of new bike
helmets manufactured by a certain company. How can we estimate
the probability of flawed helmet?
A statistic is any quantity whose value can be calculated from sample
data (e.g. s
Example for Chapter 2
Example 8 (2.2.1). Two bags, bag #1 contains two balls marked 1 and
2 respectively; bag #2 contains three balls marked 1, 2, and 3
respectively. Pick a ball from bag #1, and then pick another ball from
bag #2, how many different pos
A psychiatrist believes that 60% of all people who visit doctors have problems of a psychosomatic
nature. He decides to select 9 patients at random to test his theory. Assume the psychiatrists theory
1. What is the probabili
Examples for Chapter
Example 4 Let X be the angle measured clockwise from a reference
radius line on a circle. One possible pdf for X is
Example 5 Time headway in traffic flow is the elapsed time
between the time that one car finishes passing a fixed
Example for chapter 5
Example 25 The time that it takes a randomly selected rat of a certain
subspecies to find its way through a maze is a normally distributed rv
with = 1.5 min and = .35 min. Suppose five rats are selected.
Let X1, . . . , X5 denote t
Statistics 511, Quiz 3
The heights of men in a certain population follow a normal distribution with mean 69.7
inches and standard deviation 2.8 inches.
a) If a man is chosen at random from the population, find the probability that he wi
1. Short-answer questions.
(a) The number of contaminating particles on a silicon wafer prior to a certain rinsing
process was determined for each wafer in a sample of size 100, resulting in the
Number of particles 0
Statistics 511-8&10, Quiz 1
Consider the following observations on shear strength of a joint bonded in a particular manner:
a. Determine the v
Statistics 511-8&10, Quiz 2
An electronics store has received a shipment of 20 table radios with connections for external
devices. Twelve of them have two connection slots, and the other eight have a single slot.
Suppose that six of
b. P(A U B)=0.6+0.4-0.3=0.7
c. P(neither A nor B) =P(A B)=1-0.7=0.3
d. The event of interest is A B: from a Venn diagram, we see P(AB)=P(A)-P(AB)=0.6-0.3=0.3
e. From a Venn diagram, we see that the probability of interest is P(exactly one)=P(
Example 1 Consider a study of visual and musculoskeletal problems
associated with the use of visual display terminals (VDTs). The
accompanying representative data on y = ocular surface area (cm2)
and x = width of the horizontal width of the ey
Examples for Lecture 1
An article in the New York Times (Jan. 27, 1987) reported t
hat heart attack risk could be reduced by taking aspirin. Th
is conclusion was based on a designed experiment involvin
g both a control group of individuals th