Fifteen years ago, a complete survey of all undergraduate students at a large university indicated that the average student smoked 6.9 cigarettes per day with a standard deviation of 1.9.  The director of the student health center wishes to determine whether the incidence of cigarette smoking has lessened over the 15 year period.  He takes a random sample of 400 undergraduate students and finds their mean to be 6.4 cigarettes smoked per day.  Test the null hypothesis at the .01 level of significance.

Q: In a test of the effectiveness of garlic for lowering cholesterol, 64 subjects were treated with raw…

A: Given that  Sample size n =64  Difference of Mean =0.3 Standard deviation =16.2

Q: One year Thomas had the lowest ERA (earned-run average, mean number of runs yielded per nine innings…

A:

Q: Assuming cholesterol data indicated a mean total cholesterol level for adult persons 20 years of age…

A: The probability that a randomly selected sample of 25 adults will have a mean level < 180  is…

Q: One year Thomas had the lowest ERA​ (earned-run average, mean number of runs yielded per nine…

A: We have given that  X~N( μ , ?^2 )   Z-score =( x - μ )/?

Q: Suppose that shoe sizes of American women have a bell-shaped distribution with a mean of 8.47 and a…

A: Empirical rule: The probability that the observation under the normal curve lies within 1 standard…

Q: For a study conducted by the research department of a pharmaceutical company, 260 randomly selected…

A: We have given that Sample mean (x̅1) = 17.80Sample mean (x̅2) = 18.20Sample size (n1) = 260Sample…

Q: according to chebyshev's theorem, at least 88.9% of data will be between   Mean=15.4  Standard…

A: Chebyshev's theorem gives the minimum proportion of the data which must lie within a given number of…

Q: well-known brand of pain relief tablets is advertised to begin relief within 24 hours. A simple…

A: Solution: Given information: n=18 Sample size x=24.8 hours Sample mean μ=24 hours Population mean s=…

Q: A researcher is interested in examining the effect of emotions on those that are convicted of a…

A: Group 1(violent offenders): n1=34x¯1=33.5s1=3.5 Group 2(non-violent offenders): n2=25x¯2=35s2=3…

Q: 4. Felician University uses hundreds of fluorescent light bulbs each year. The brand of bulb it…

A: The mean lifetime of current brand that it uses is of 900 hours. The mean and standard deviation of…

Q: Ten years ago, the mean age of death row inmates was 44.9 according to the US Dept.of Justice. A…

A: The provided data is,

Q: A researcher measures the lengths of 3-year-old yellow perch in a fish hatchery and finds that they…

A: From the provided information, Mean (µ) = 17.2 Standard deviation (σ) = 3.4 X~N (17.2, 3.4)

Q: According to the Center for Disease Control and Prevention (CDC), the mean life expectancy in 2015…

A:

Q: The weights of weekly plastic waste from a random sample of 50 American households resulted in a…

A: Given,sample size(n)=50sample mean(x¯)=1.91standard deviation(σ)=1.07α=0.05H0:μ=1.8H1:μ>1.8

Q: According to a recent survey, the population distribution of number of years of  education for…

A: What is the standard error of mean?

Q: According to the Center for Disease Control and Prevention (CDC), the mean life expectancy in 2015…

A: Given Data Population Mean,μ = 76.3 Population Standard Deviation,σ = 15.0 sample…

Q: For a study conducted by the research department of a pharmaceutical company, 225 randomly selected…

A: It was stated that a study was conducted on a pharmaceutical company by the research department. A…

Q: For a study conducted by the research department of a pharmaceutical company, 245 randomly selected…

A: Data given n1=245 , sample mean x̄1= 17.8 and s1= 4.3 n2=225, sample mean x̄2=18.2 amd s2= 3.60

Q: In a study entitled How Undergraduate Students Use Credit Cards, it was reported that undergraduate…

A: Given that, sample size n=100 sample mean credit card balance x¯=3506 Population standard deviation…

Q: A market research firm reported that the mean annual earnings of all family practitioners in the…

A:

Q: Suppose that shoe sizes of American women have a bell-shaped distribution with a mean of 8.36 and a…

A:

Q: In a recent poll, the Gallup organization found that 45% of adult Americans believe that the overall…

A: Binomial distribution:A random variable Y denoting the number of successes in n trials for…

Q: A paper describes asrvey ofasample of e maie students and a sampie of 5 female students ata large…

A:

Q: mean of $5.02 and a standard deviation of $0.09. Using the Empirical rule, find the range in which…

A: Given data: Mean and standard deviation of the hourly wages of employees is: μ=$5.02σ=$0.09 The…

Q: For a study conducted by the research department of a pharmaceutical company, 265 randomly selected…

A:

Q: Suppose the scores of students on an exam are normally distributed with a mean of 454 and a standard…

A:

Q: A developmental psychologist would like to know whether success in one specific area can affect a…

A:

Q: A research study examined the effects of meditation on quality of sleep. Fifty individuals were…

A:

Q: For a study conducted by the research department of a pharmaceutical company, 205 randomly selected…

A: Given Sample size n1=205, sample mean x̄1=17.6, s1=sample standard deviations=5.3,  n2=sample size…

Q: restaurant association says the typical household in the United States spends a mean amount of $3095…

A: Given that Clam : The typical household in the United States spends a mean amount of $3095 per year…

Q: Two samples of 103 and 80 students are taken with a view to find out their average monthly…

A:

Q: Fran is training for her first marathon, and she wants to know if there is a significant difference…

A: Given data,n1=40x1=46.6σ1=4.6n2=45x2=48.8σ2=2.4Compute value of test statistic?

Q: Suppose that shoe sizes of American women have a bell-shaped distribution with a mean of 8.47 and a…

A:

Q: According to the Center for Disease Control and Prevention (CDC), the mean life expectancy in 2015…

A: Given Data Population Mean,μ = 71.8 Population Standard Deviation,σ = 15.0 sample…

Q: A sociologist claims that mean height of all adult women in Smallville is more than 64 inches. In a…

A: Given data is appropriate for testing of hypothesis for testing z-test for single mean. Because it…

Q: A​ half-century ago, the mean height of women in a particular country in their 20s was 64.7 inches.…

A: Given that: X is normal Distributed with mean µ = 64.7 and standard deviation σ = 2.88 By using…

Q: An engineer would like to design a parking garage in the most cost-effective manner. He reads that…

A: Given information Hypothesized mean µ = 76.4 inches Sample size (n) = 100 Mean x̅ = 77.1 inches…

Q: In 2002, the mean age of an inmate on death-row was 40.7 years, according to data from the US…

A:

Q: The National Collegiate Athletic Association (NCAA) requires Division I athletes to score at least…

A:

Q: Suppose the scores of students on an exam are normally distributed with a mean of 558 and a standard…

A:

Q: Suppose the scores of students on an exam are normally distributed with a mean of 253 and a standard…

A: From the provided information, Mean (µ) = 253 Standard deviation (σ) = 80

Q: For a study conducted by the research department of a pharmaceutical company, 235 randomly selected…

A: Given n1=235 n2=250 X1-bar=17.80 X2 bar=18.20

Q: Researchers at a medical center studied the amount of caffeine, in milligrams (mg), contained in a…

A: Given x=159.88 and s = 36.72; n=40 Confidence interval =x±tαsn                                  =…

Q: In a research study, conducted by the National Institute of Health, 25 individuals were sampled…

A: From the given information, In a research study, conducted by the National Institute of Health, 25…