A test on car braking reaction times for men between 18 and 30 years old has produced a mean and standard deviation of 0.63 and 0.143 seconds respectively. When 40 male drivers of this age group were randomly selected and tested for their braking reaction times, a mean of 0.578 second came out. At the level of significance 0.01, test the claim of the driving instructor that his graduates had faster reaction time.
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A test on car braking reaction times for men between 18 and 30 years old has produced a mean and standard deviation of 0.63 and 0.143 seconds respectively. When 40 male drivers of this age group were randomly selected and tested for their braking reaction times, a mean of 0.578 second came out. At the level of significance 0.01, test the claim of the driving instructor that his graduates had faster reaction time.
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- A new small business wants to know if its current radio advertising is effective. The owners decide to look at the mean number of customers who make a purchase in the store on days immediately following days when the radio ads are played as compared to the mean for those days following days when no radio advertisements are played. They found that for 11 days following no advertisements, the mean was 16.6 purchasing customers with a standard deviation of 1.1 customers. On 10 days following advertising, the mean was 17.7 purchasing customers with a standard deviation of 1.4 customers. Test the claim, at the 0.02 level, that the mean number of customers who make a purchase in the store is lower for days following no advertising compared to days following advertising. Assume that both populations are approximately normal and that the population variances are equal. Let days following no advertisements be Population 1 and let days following advertising be Population 2. Step 2 of 3 : Compute…A researcher wanted to know whether losing one night sleep can affect problem solving. A sample of n = 25 college students was given a problem-solving task at noon on one day and again at noon on the following day. The students were not permitted any sleep between the two tests. For each student, the difference between the first and the second score was recorded: MD = 5 and standard deviation of the difference score was s = 10. Do the data indicate a significant change in problem solving ability? Use a two-tailed test with α = .01. a. The alternative hypothesis in words is b. The null hypothesis in symbols is c. The critical t-values are d. The t-statistic is e. Your decision isFor a new study conducted by a fitness magazine, 280 females were randomly selected. For each, the mean daily calorie consumption was calculated for a September-February period. A second sample of 240 females was chosen independently of the first. For each of them, the mean daily calorie consumption was calculated for a March-August period. During the September-February period, participants consumed a mean of 2385.7 calories daily with a standard deviation of 210. During the March-August period, participants consumed a mean of 2414.3 calories daily with a standard deviation of 285. The population standard deviations of daily calories consumed for females in the two periods can be estimated using the sample standard deviations, as the samples that were used to compute them were quite large. Construct a 90% confidence interval for u, -u,, the difference between the mean daily calorie consumption u, of females in September-February and the mean daily calorie consumption u, of females in…
- Assume that adults have IQ scores that are normally distributed with a mean of 103.8 and a standard deviation 15.7. Find the first quartile Q1, which is the IQ score separating the bottom 25% from the top 75%. The first quartile isA simple random sample of 36 observations was taken from a large population. The sample mean and the standard deviation was determined to be 80 and 12 respectively. What is the standard error of the mean?Fran is training for her first marathon, and she wants to know if there is a significant difference between the mean number of miles run each week by group runners and individual runners who are training for marathons. She interviews 37 randomly selected people who train in groups, and finds that they run a mean of 47.7 miles per week. Assume that the population standard deviation for group runners is known to be 3.3 miles per week. She also interviews a random sample of 49 people who train on their own and finds that they run a mean of 49.4 miles per week. Assume that the population standard deviation for people who run by themselves is 4.4 miles per week. Test the claim at the 0.10 level of significance. Let group runners training for marathons be Population 1 and let individual runners training for marathons be Population 2. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.
- Fran is training for her first marathon, and she wants to know if there is a significant difference between the mean number of miles run each week by group runners and individual runners who are training for marathons. She interviews 42 randomly selected people who train in groups and finds that they run a mean of 47.1 miles per week. Assume that the population standard deviation for group runners is known to be 4.4 miles per week. She also interviews a random sample of 47 people who train on their own and finds that they run a mean of 48.5 miles per week. Assume that the population standard deviation for people who run by themselves is 1.8 miles per week. Test the claim at the 0.01 level of significance. Let group runners training for marathons be Population 1 and let individual runners training for marathons be Population 2. Step 2 of 3 : Compute the value of the test statistic. Round your answer to two decimal places.Suppose that an independent research company was tasked with testing the validity of complaints against a pesticide manufacturing firm for under-filling their 20 lb bags of pesticide. Past experience has shown that the amount of pesticide dispensed by the machines that fill the bags follows a normal distribution with a mean of 20 lb and a standard deviation of 0.6 lb. To verify the validity of the complaints, a researcher randomly selected 16 of the firm's 20 lb pesticide bags and recorded the following weights. 19.69, 19.5, 18.85, 18.56, 20.23, 20.3, 20.14, 19.11, 19.65, 18.87, 19.22, 19.24, 18.82, 20.23, 20.46, 18.66 If you wish, you may download the data in your preferred format. CrunchIt! CSV Excel JMP Mac Text Minitab PC Text R SPSS TI Calc The mean weight of the 16 bags collected was 19.471 lb. Calculate the value of the one-sample z- statistic. Give your answer precise to three decimal places.Bone mineral density (BMD) is a measure of bone strength. Studies show that BMD declines after age 45. The impact of exercise may increase BMD. A random sample of 59 women between the ages of 41 and 45 with no major health problems were studied. The women were classified into one of two groups based upon their level of exercise activity: walking women and sedentary women. The 39 women who walked regularly had a mean BMD of 5.96 with a standard deviation of 1.22. The 20 women who are sedentary had a mean BMD of 4.41 with a standard deviation of 1.02. Which of the following inference procedures could be used to estimate the difference in the mean BMD for these two types of women
- Pilots who cannot maintain regular sleep hours due to their work schedule often suffer from insomnia. A recent study on sleeping patterns of pilots focused on quantifying deviations from regular sleep hours. A random sample of 28 commercial airline pilots was interviewed, and the pilots in the sample reported the time at which they went to sleep on their most recent working day. The study gave the sample mean and standard deviation of the times reported by pilots, with these times measured in hours after midnight. (Thus, if the pilot reported going to sleep at p.m., the measurement was -1.) The sample mean was 0.8 hours, and the standard deviation was 1.6 hours. Assume that the sample is drawn from a normally distributed population. Find a 90% confidence interval for the population standard deviation, that is, the standard deviation of the time (hours after midnight) at which pilots go to sleep on their work days. Then give its lower limit and upper limit.A new small business wants to know if its current radio advertising is effective. The owners decide to look at the mean number of customers who make a purchase in the store on days immediately following days when the radio ads are played as compared to the mean for those days following days when no radio advertisements are played. They found that for 7 days following no advertisements, the mean was 22.1 purchasing customers with a standard deviation of 1.2 customers. On 10 days following advertising, the mean was 24.1 purchasing customers with a standard deviation of 1.6 customers. Test the claim, at the 0.05 level, that the mean number of customers who make a purchase in the store is lower for days following no advertising compared to days following advertising. Assume that both populations are approximately normal and that the population variances are equal. Let days following no advertisements be Population 1 and let days following advertising be Population 2. Step 1 of 3: State the…A new small business wants to know if its current radio advertising is effective. The owners decide to look at the mean number of customers who make a purchase in the store on days immediately following days when the radio ads are played as compared to the mean for those days following days when no radio advertisements are played. They found that for 13 days following no advertisements, the mean was 23.9 purchasing customers with a standard deviation of 1.9 customers. On 6 days following advertising, the mean was 24.7 purchasing customers with a standard deviation of 1.6 customers. Test the claim, at the 0.01 level, that the mean number of customers who make a purchase in the store is lower for days following no advertising compared to days following advertising. Assume that both populations are approximately normal and that the population variances are equal. Let days following no advertisements be Population 1 and let days following advertising be Population 2. Step 3 of 3: Draw a…