In a population of fish, approximately 42% are female. A test is conducted to see if, in
fact, the proportion is less. State the null and alternative hypotheses
Ans
H0: p = 0.42
Ha: p < 0.42
The mean entry level salary of an employee at a company is $58,000. You believe it is
higher for IT professionals in the company. State the null and alternative hypotheses.
Ans
H0: = 58,000
Ha: > 58,000
The American family has an average of two children. What is the random variable? Describe in words.
Ans
The random variable is the mean number of children an American family has.
You are testing that the mean speed of your cable Internet connection is more than
three Megabits per second. State the null and alternative hypotheses.
Ans
H0: 3 Ha: > 3
For Exercise 9.12, what are and in words?
Ans
= the probability that you think the bag cannot withstand -15 degrees F, when in fact it can = the
probability that you think the bag can withstand -15 degrees F, when in fact it cannot
Which distribution do you use when the standard deviation is not known and you are testing one
population mean? Assume sample size is large.
Ans
Use a Students t-distribution.
The probability of winning the grand prize at a particular carnival game is 0.005. Michele wins the grand
prize. Is this considered a rare or common event? Why?
Ans
This is considered a rare event because the probability of it occurring is so low.
In words, describe 1 for Exercise 9.12.
Ans
1 is 1 the probability of a Type II error. It represents the power of the test. A valid test will have a
high power; therefore, a low probability of a Type II error.
It is believed that Lake Tahoe Community College (LTCC) Intermediate Algebra students
get less than seven hours of sleep per night, on average. A survey of 22 LTCC Intermediate
Algebra students generated a mean of 7.24 hours with a standard deviation of 1
A group of doctors is deciding whether or not to perform an operation. Suppose the null hypothesis, H0,
is: the surgical procedure will go well. State the Type I and Type II errors in complete sentences.
Ans
Type I: The procedure will go well, but the doc
A sleeping bag is tested to withstand temperatures of -15 F. You think the bag cannot stand
temperatures that low. State the Type I and Type II errors in complete sentences.
Ans
Type I: The bag can withstand -15 F, but you conclude that it cannot stand te
The mean price of mid-sized cars in a region is $32,000. A test is conducted to see if the claim is true.
State the Type I and Type II errors in complete sentences.
Ans
Type I: The mean price of mid-sized cars is $32,000, but we conclude that it is not $3
A random survey of 75 death row inmates revealed that the mean length of time on death row is 17.4
years with a standard deviation of 6.3 years. If you were conducting a hypothesis test to determine if the
population mean time on death row could likely be
A sociologist claims the probability that a person picked at random in Times Square in New York City is
visiting the area is 0.83. You want to test to see if the claim is correct. State the null and alternative
hypotheses.
Ans
H0: p = 0.83
Ha: p 0.83
A sociologist claims the probability that a person picked at random in Times Square in
New York City is visiting the area is 0.83. You want to test to see if the proportion is
actually less. What is the random variable? Describe in words.
Ans
The random v
A group of doctors is deciding whether or not to perform an operation. Suppose the null hypothesis, H0,
is: the surgical procedure will go well. Which is the error with the greater consequence?
Ans
The Type II error has the greater consequence because the
A microbiologist is testing a water sample for E-coli. Suppose the null hypothesis, H 0, is: the
sample does not contain E-coli. The probability that the sample does not contain E- coli, but the
microbiologist thinks it does is 0.012. The probability that
A microbiologist is testing a water sample for E-coli. Suppose the null hypothesis, H0, is: the sample
contains E-coli. Which is the error with the greater consequence?
Ans
A Type I error has the greater consequence. Thinking there are no E-coli when ther
A statistics instructor believes that fewer than 20% of Evergreen Valley College (EVC) students attended
the opening night midnight showing of the latest Harry Potter movie. She surveys 84 of her students and
finds that 11 attended the midnight showing.
A
A group of divers is exploring an old sunken ship. Suppose the null hypothesis, H0, is: the sunken ship
does not contain buried treasure. State the Type I and Type II errors in complete sentences
Ans
Type I: The ship does not contain buried treasure, but
The mean age of graduate students at a University is at most 31 y ears with a standard deviation of two
years. A random sample of 15 graduate students is taken. The sample mean is 32 years and the sample
standard deviation is three years. Are the data sig