To estimate the effect of CD writing, 30 users are asked to work on their laptops until the “low battery” sign comes on. Eighteen users without a CD writer worked an average of 5.3 hours with a standard deviation of 1.4 hours. The other twelve, who used their CD writer, worked an average of 4.8 hours with a standard deviation of 1.6 hours. Assuming Normal distributions with equal population variances, does a CD writer change the battery life on a laptop? Alpha=0.10.

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Answered: To estimate the effect of CD writing,…

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

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A number of 28 university students who smokes completed a questionnaire inquiring their smoking history and behavior. The result shows that the average smoking initiation age of this group is 21.6 years with a variance of 18.49. Based on past record, the smoking initiation age of university student has a mean of 20.74 years with a standard deviation of 5.1 years. Conduct a necessary analysis to determine if the smoking initiation age remain the same as the previous record. Use 4% level of significance.
A survey found that women's heights are normally distributed with mean 62.3 inches and standard deviation 2.2 inches. Most of the live characters employed at an amusement park have height requirements of at least 54 inches Find the percentage of women meeting the height requirement?
A researcher collected data from Boston police officers and found that on average they spent 14.3 hours on in-service training per year with a standard deviation of 3.2. The department offers bonuses for officers in the top 10 percent on in-service training completed. Would the officer who did 22 hours of training get the bonus?
An analyst found that the average amount of money in bank accounts at his/her bank is $2,000 with a standard deviation of $150. What would be the variance?
The heights of 10 year old American children are normally distributed with a mean height of 4 feet and 5 inches (or 53 inches) and a standard deviation of 4.5 inches.In order to be allowed to go on a particular kids ride at the amusement park, children must be at least 44.9 inches tall and no more than 59.75 inches tall.What percent of 10 year old American children cannot go on the ride?
A sports writer wants to see if a football filled with helium travels farther, on average, than a football filled with air. 12 footballs were filled with helium to the recommend pressure and 15 footballs were filled with air to the recommended pressure. The mean yardage for the helium filled footballs was 267 yards with a standard deviation of 3 yards. The mean yardage for the air filled footballs was 241 yards with a standard deviation of 5 yards. Assume the populations are normal with equal variances. (a). Construct a 99% confidence interval for the mean difference in in yardage for the two types of footballs Lower bound (use 3 decimal places) Upper bound (use 3 decimal places) (b). What can you conclude about the sports writer's idea that helium footballs travel farther, on average? The helium footballs are no different than the other footballs, on average The other footballs travel farther on average than the helium footballs The helium footballs travel farther on average than the…
In a certain country the heights of adult men are normally distributed with a mean of 67.2 inches and a standard deviation of 2.3 inches. The country's military requires that men have heights between 64 inches and 75 inches. Determine what percentage of this country's men are eligible for the military based on height.
A survey among freshmen at a certain university revealed that the number of hours spent studying the week before final exams was normally distributed with mean 25 and standard deviation 9. Between what two values are the middle 80% of the hours spent studying?
A blood bank is conducting a study on how much time is required of their patients for blood platelet donations. Based on past records, time spent in the waiting room has a mean of 5 minutes and a standard deviation of 1 minute, time spent with a nurse who reviews patients' medical records and measures their vital signs has a mean of 10 minutes and a standard deviation of 3 minutes, and the actual donation time has a mean of 130 minutes and a standard deviation of 8 minutes. Assuming these three times are independent and can all be modeled using a normal distribution, approximately what proportion of donors finish the entire donation process in under 2.5 hours (150 minutes)? (A) 0.66 (B) 0.72 (C) 0.84 (D) 0.89 (E) 0.99
It appears that people who are mildly obese are less active than leaner people. One study looked at the average number of minutes per day that people spend standing or walking. Among mildly obese people, the mean number of minutes of daily activity (standing or walking) is approximately Normally distributed with 371 minutes and standard deviation 69 minutes. The mean number of minutes of daily activity for lean people is approximately Normally distributed with 526 minutes and standard deviation 106 minutes. A researcher records the minutes of activity for an SRS of 6 mildly obese people and an SRS of 6 lean people. (a) What is the probability that the mean number of minutes of daily activity of the 6 mildly obese people exceeds 410 minutes? (Enter your answer rounded to four decimal places.) probability: 0.0256 Incorrect (b) What is the probability that the mean numberpof minutes of daily activity of the 6 lean people exceeds 410 minutes? (Enter your answer rounded to four decimal…
The ACCUPLACER is a college readiness exam. The scores for the math section are normally distributed with a mean of 75 and standard deviation of 8. A college policy is that the bottom 15% of test takers are required to take a remedial math course over the summer. Students who score below what score will have to take the summer course?

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