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##### Statstics exam

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Question;Statistical inference takes information from;the ___________ and makes inferences to the ____________.;A) sample;populationB) population;sample C) neither;4. Suppose that a 95% confidence interval for;the proportion of first-year students at a school who played in intramural;sports is 35% plus or minus 5%. The 95% confidence interval for the proportion;of students playing intramural sports is;A)25% to 45%B)30% to 35%C)35% to 40%D)30% to 40%;6.;In a past General;Social Survey, 22% of n = 1006 respondents answered yes to the question;Are you a member of any sports groups?" A 95% confidence interval;for the population proportion of Americans who belonged to a sports group at;that time is 19.4% to 24.6%. Based on these results, you can reasonably;conclude that;A)22% is an acceptable possibility for;the proportion of all Americans belonging to sports clubs, but 20% is;not.B)Neither 20% nor 22% are acceptable;possibilities for the proportion of all Americans belonging to sports clubs.C)Both 20% and 22% are acceptable;possibilities for the proportion of all Americans belonging to sports clubs.;7. What is the primary purpose of a 95%;confidence interval for a mean?;A) to;estimate a sample mean B) to;test a hypothesis about a sample mean C) to;estimate a population meanD) to;provide an interval that covers 95% of the individual values in the;population A;randomly selected sample of n = 51 men in Brazil had an average lifespan of 59;years. The standard deviation was 10 years, and the standard error of the mean;is 1.400. Calculate a 90% confidence interval for the average lifespan for all;men in Brazil.;A)(42.2, 75.8)B)(56.6, 61.4)C)(56.2, 61.8);A null hypothesis is that the probability is;0.7 that a new drug will provide relief in a randomly selected patient. The;alternative is that the probability of relief is greater than;0.7. Suppose the treatment is used on 500 patients and there are 380 successes.;How would a p-value be calculated in this situation?;A)Find the chance of 380 or more;successes, calculated assuming the true success rate is greater than 0.7.B)Find the chance of 380 or more;successes, calculated assuming the true success rate is 0.7.C)Find the chance of fewer than 380;successes, calculated assuming the true success rate is greater than 0.7.D)Find the chance of fewer than 380;successes, calculated assuming true success rate is 0.7.;A hypothesis test is done in which the;alternative hypothesis states that more than 10% of a population is;left-handed. The p-value for the test is calculated to be 0.25. Which statement;is correct?;A) We;can conclude that more than 10% of the population is left-handed. B) We;can conclude that more than 25% of the population is left-handed. C) We;can conclude that exactly 25% of the population is left-handed. D) We;cannot conclude that more than 10% of the population is left-handed.;A hypothesis test for a population proportion;? is given below;Ho:? = 0.10 Ha:?? 0.10;If the sample size n = 500 and sample;proportion?-hat = 0.20, then the z-statistic is;A)-7.45B)-5.59C)5.59D)7.45;Suppose a 95% confidence interval for p, the;proportion of drivers who admit that they sometimes run red lights when no one;is around, is 0.29 to 0.38. Which of the following statements is false?;A) A;test of Ho:? = 0.3 versus Ha:?? 0.3 would not be rejected using a =;0.05. B) A;test of Ho:? = 0.5 versus Ha:?? 0.5 would be rejected using a = 0.05. C) It;is plausible that about 37% of all drivers would admit that they sometimes run;red lights when no one is around. D) It;is plausible that a majority of all drivers would admit that they sometimes run;red lights when no one is around.A safety officer wants;to prove that? = the average speed of cars driven by a school is less than 25;mph. Suppose that a random sample of 14 cars shows an average speed of 24.0;mph, with a sample standard deviation of 2.2 mph. Assume that the speeds of cars;are normally distributed. What are the appropriate null and alternative;hypotheses?;A) Ho:? = 25 and Ha:? 25;C) Ho:? = 25 and Ha;?? 25;D) Ho:?? 25 and Ha;? = 25;E) Ho: x-bar = 24 and;Ha: x-bar 24;G) Ho: x-bar = 24 and;Ha: x-bar? 24;H) Ho: x-bar? 24 and;Ha: x-bar = 24;A counselor wants to show that for men who;are married by the time they are 30,? = average age when the men are married;is not 21 years old. A random sample of 10 men who were married by age 30;showed an average age at marriage of 22.2, with a sample standard deviation of;1.9 years. Assume that the age at which this population of men gets married for;the first time is normally distributed. What is the value of the test;statistic?;A) t =1.80;B) t =2.00;C) t =2.33;A counselor wants to show that for men who;are married by the time they are 30,? = average age when the men are married;is not 21 years old. A random sample of 10 men who were married by age 30;showed an average age at marriage of 22.2, with a sample standard deviation of;1.9 years. Assume that the age at which this population of men gets married for;the first time is normally distributed. Using the T-table, and a significance;level of a = 0.05, which of the following is an appropriate conclusion?;A) The results are statistically;significant so the average age appears to be greater than 21.;B) The results are statistically;significant so the average age appears to be less than 21.;C) The results are not statistically significant so there;is not enough evidence to conclude average age is different from 21.It is known that for right-handed people, the;dominant (right) hand tends to be stronger. For left-handed people who live in;a world designed for right-handed people, the same may not be;true. To test this, muscle strength was measured on the right and left hands of;a random sample of 15 left-handed men and the difference (left - right) was;found. The alternative hypothesis is one-sided (left hand stronger). The;resulting t-statistic was 1.90. This is an example of;A)a two-sample t-test.B)a paired t-test.C)a pooled t-test.D)an unpooled t-test.Which of the following is not one;of the assumptions made in the analysis of variance?;A)Each sample is an independent random;sample.B)The distribution of the response;variable is a normal curve within each population.C)The different populations all have the;same mean.D)The different populations all have;the same population variances.;Which of these situations could be analyzed;with a one-way analysis of variance?;A)The relationship between gender;(male or female) and opinion about the death penalty (favor, oppose;uncertain)B)The relationship between weight and;height for 12-year old girlsC)A comparison of four different age;groups with regard to mean hours of watching television per dayD)A comparison of four different age;groups with regard to proportion that opposes legalization of marijuana;A student wanted to test whether there was a;difference in the mean daily hours of study for students living in four;different dormitories. She selected a random sample of 50 students from each of;the four dormitories. What is the null hypothesis for this situation?;A) The;mean daily hours of study is 3 hours for each dormitory. B) The;mean daily hours of study is the same for each dormitory.C) The;mean daily hours of study is different for each of the 200 students in the;sample. D) The;mean daily hours of study is not the same for all four dormitories.;A study compared grade point averages (GPA);for students in a class: students were divided by 6 locations where they;usually sat during lecture (i.e. left or right front, left or right center;left or right rear). A total sample size of 12 students was studied (2 students;from each section) using one-way analysis of variance. The p-value for the;F-test is 0.46. If the significance level,?, is 0.05, what is the conclusion?;A)The null hypothesis is not rejected so;we cannot say the population means are different.B)The null hypothesis is not rejected;so we can say the population means are different.C)The null hypothesis is rejected so;we cannot say the population means are different.D)The null hypothesis is rejected so;we can say the population means are different.E)The null hypothesis is not rejected;so we cannot say the sample means are different.F)The null hypothesis is not rejected;so we can say the sample means are different.G)The null hypothesis is rejected so;we cannot say the sample means are different.H)The null hypothesis is rejected so;we can say the sample means are different.;Five different training;programs for improving endurance are compared. Forty individuals are randomly;divided into five groups of n = 8 each and a different training program is;assigned to each group. After two months, the improvement in endurance is;recorded for each participant. A one-way analysis of variance is used to;compare the five training programs, and the resulting p-value is 0.023. At a;significance level of 0.05, the appropriate conclusion about mean improvement;in endurance is that it;A) is the same for the;five training programs.;B) is different for each;of the five training programs;C) differs for at least two of the five training;programs.;D) is significantly;better for one of the training programs than for the other four.If the correlation between a response variable;Y and explanatory variable X is - 0.5, what is the value that;defines how much variation in Y is explained by X?;A) 25%B) 5% C) -;25% D) -;5%;Which of the following variables would;typically NOT be used as the response variable;for linear regression?;A)GenderB)AgeC)HeightD)GPA;Which of the following can not be answered;from a regression equation?;A) Predict the value of y at a particular;value of x.;B) Estimate the slope between y and x.;C) Estimate whether the linear association;is positive or negative.;D) Estimate whether the association is linear or;non-linear;A regression was done for 20 cities with;latitude as the explanatory variable (x) and average January temperature as the;response variable (y). The latitude is measured in degrees and average January;temperature in degrees Fahrenheit. The latitudes ranged from 26 (Miami) to 47;(Duluth) The regression equation is;y = 49.4 - 0.313x;Mexico City has latitude 20 degrees. What;is the problem with using the regression equation to estimate the average;January temperature for Mexico City?;A) Nothing, since Mexico City is a city;B) Mexico City is a city not found in the;U.S.;C) The regression equation is based on 20 cities, with;the lowest latitude being 26 degrees.;A reviewer rated a sample of fifteen wines;on a score from 1 (very poor) to 7 (excellent). A correlation of 0.92 was;obtained between these ratings and the cost of the wines at a local store. In;plain English, this means that;A) in general, the reviewer liked the;cheaper wines better.;B) having to pay more caused the reviewer;to give a higher rating.;C) wines with low ratings are likely to be;more expensive (probably because fewer will be sold).;D) in general, as the cost went up so did the rating.;A study is conducted comparing a student's;height versus the height of their father. The correlation between father?s;heights and student?s heights for 79 male students was r = 0.669. What is the;proportion of variation in son?s heights explained by the linear relationship;with father?s heights?;A) 44.8%;B) 82.0%;C) ? 44.8%;D) ? 82.0%;Based on 1988 census data for the 50 States;in the United Stares, the correlation between the number of churches per State;and the number of violent crimes per State was 0.85. What can we conclude?;A) There is a causal relationship between;the number of churches and the number of violent crimes committed in a city.;B) The correlation is spurious because of the confounding;variable of population size: both number of churches and number of violent;crimes are related to the population size.;C) Since the data comes from a census, or;nearly complete enumeration of the United States, there must be a causal;relationship between the number of churches and the number of violent crimes.;D) The relationship is not causal because;only correlations of +1 or - 1 show causal relationships.

Paper#62156 | Written in 18-Jul-2015

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