Ch. 6 Binomial
As reported by the Television Bureau of Adversiting, Inc. in Trends in Television 84% of US households have a DVD player. If 500 households are randomly selected, what is the expected number of househjolds that have a DVD player?
420
Yearling Angus steers have weights that follow a normal model with mean weight 1152 pounds and standard deviation 84 pounds. What percent of steers weigh less than 1200 pounds? A. 57% B. 71.57% C. 28.43% D. 43%
B. 71.57%
How do we solve for a point estimate when we already have an interval? What about margin of error? (HINT-page 85)
Point Estimate- LB+UB/2
ME- UB-LB/2
If you reject the null there is _________ evidence Ho is possible.
sufficient/enough
insufficient/not enough
sufficient/enough
Thirty-one percent of adults say baseball is their favorite sport. A random sample of 12 persons is selected.
What is the standard deviation of the number whose favorite sport is baseball?
A. 3.72 B. 8.28 C. 2.5668 D. 1.6021 E. None of these
D. 1.6021
Suppose 98% of Americans celebrate a particular holiday with family. A random sample of 100 Americans is selected. Can we use the normal approximation to estimate the probability that exactly two celebrate this holiday with family? A. Yes: np is greater than 10. B. Yes: n is large. C. No: n(1-p) is too small. D. No: 100 is less than 10% of Americans.
C. No: n(1-p) is too small.
Suppose that 20% of the subscribers of a cable television company watch the shopping channel at least once a week. The cable company is trying to decide whether to replace this channel with a new local station. A survey of 100 subscribers will be undertaken. The cable company has decided to keep the shopping channel if the sample proportion is greater than 0.2. Describe the sampling distribution of the sample proportion of subscribers who watch the shopping channel at least once a week.
p-hat~AN(.2,.04)
What is the definition of a p-value?
The probability that the test statistic takes a value as extreme or more extreme than that actually observed, if the null hypothesis is true.
Thirty-one percent of adults say baseball is their favorite sport. A random sample of 12 persons is
selected.
6. Find the probability that at least two of the 12 persons say baseball is their favorite sport.
A. 0.2296 B. 0.0744 C. 0.1551 D. 0.9256 E. None of these
D. 0.925
According to the Air Transport Association of America, the average operating cost of an MD-80 jet airliner is $2087 per hour. Suppose the operating costs of an MD-80 jet airliner are normally distributed with a standard deviation of $175 per hour.
. What is the probability that a randomly selected MD-80 jet airliner costs more than $2500 per hour to operate? A. 0.0091 B. 2.36 C. -2.36 D. 0.9909
A. 0.0091
Suppose that 20% of the subscribers of a cable television company watch the shopping channel at least once a week. The cable company is trying to decide whether to replace this channel with a new local station. A survey of 100 subscribers will be undertaken. The cable company has decided to keep the shopping channel if the sample proportion is greater than 0.25. What is the probability that the proportion that watch the shopping channel at least once a week, in a SRS of 100 subscribers, is greater than 0.25?
.1056
Suppose in a hypothesis test, the probability of committing a Type II error was decreased. Which of the following is correct? A. The probability of committing a Type I error would be decreased B. The level of significance would be decreased C. The power of the test would be decreased D. The power of the test would be increased
D. The power of the test would be increased
Markus wants to go surfing for two hours this Sunday and is thinking about how many waves he will catch. He estimates that the probability of catching no waves during that time is 0.1,the probability of catching one wave is 0.1, the probability of catching two waves is 0.2 and the probability of catching four or more waves is 0.4. According to these estimates, what is the probability that Markus will catch 3 waves?
A. 0.2 B. 0.3 C. 0.1 D. 0.4 E. Cannot calculate
A. 0.2
A standardized test is normally distributed with mean 500 and standard deviation 20. Which of the following values would be considered unusual? A. 515 B. 470 C. 450 D. 525 E. both B & C
C. 450
If we calculate a 95% confidence interval instead of a 99% confidence interval, then: a) The width of the confidence interval would be unchanged. b) The confidence interval width would decrease. c) The confidence interval width would increase.
b) The confidence interval width would decrease.
In leaving for school on an overcast April morning, you need to decide whether to take an umbrella. If the null hypothesis is that the weather will remain dry, then which of the following would be an example of a Type II error? A. When you leave for school, you choose not to take an umbrella and you get drenched. B. When you leave for school, you choose not to take an umbrella and the weather remains dry. C. When you leave for school, you choose to take an umbrella and you carry it around needlessly. D. When you leave for school, you choose to take an umbrella and it rains.
A. When you leave for school, you choose not to take an umbrella and you get drenched.
The scores on a nationally administered test are normally distributed with a mean of 63 and
standard deviation 8. Use the Empirical Rule to answer the following questions.
1. What percentage of students scored between 47 & 87?
A. 97.35 % B. 99.7% C. 81.5% D. 83.85% E. 95%
A. 97.35
According to the Air Transport Association of America, the average operating cost of an MD-80 jet airliner is $2087 per hour. Suppose the operating costs of an MD-80 jet airliner are normally distributed with a standard deviation of $175 per hour.
9. In what interval would the middle 70% of operating costs fall? A. -0.52, 0.52 B. $1996, $2178 C. -1.04, 1.04 D. $1905, $2269 E. None of the above
D. $1905, $2269
A statistician calculates a 95% confidence interval for the true proportion of people who believe that affirmative action should continue. The confidence interval is 0.499 to 0.561. What sample size was used to calculate this confidence interval?
a.900 b.995 c.996 d.1000
c.996
You collect data and test the hypotheses H0 : p= 0.50 Ha : p =/= 0.50 A P-value of 0.06 is obtained. Which of the following is true? A. A 99% confidence interval for p will not include the value 0.50. B. A 95% confidence interval for p will not include the value 0.50. C. A 90% confidence interval for p will not include the value 0.50. D. We cannot make a decision using the information given.
C. A 90% confidence interval for p will not include the value 0.50