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The life of an automobile battery is known to follow normal distribution with a mean of...
If the lifetime X of a certain kind of automobile battery is normally distributed with mean...
If the lifetime X of a certain kind of automobile battery is normally distributed with mean of 3 years and standard deviation of 1 year, and the manufacturer wishes to guarantee the battery for 2 years, what percentage of the batteries will he have to replace under the guarantee? 5.
15. A certain type of automobile battery is known to have a lifetime which is normally...
15. A certain type of automobile battery is known to have a lifetime which is normally distributed with mean 1,200 days and standard deviation 90 days. For how many days should these batteries be guaranteed if the manufacturer wants to replace only 20% of the batteries sold because they "died" before the guarantee expired? A. 1052 B. 1105 C. 1124 D. 1094 16. A particular television commercial is understood by 30% of first graders and 65% of fourth graders....
9. The service life of automobile tires is modeled by a normal curve; the Mean Time...
9. The service life of automobile tires is modeled by a normal curve; the Mean Time Between Failures (MTBF) is 20,000 miles and the standard deviation is 800 miles. Use Table B in Appendix B (page 868 and 869) to solve these problems. a. Determine the probability that a tire will fail before 22,000 miles. (2.5 point) Answer: b. Determine the probability that a tire will last at least 19,000 miles. (2.5 point) Answer: c. The manufacturer wishes to provide...
A certain type of automobile battery is known to last an average of 1,180 days with...
A certain type of automobile battery is known to last an average of 1,180 days with a standard deviation of 50 days. If 100 of these batteries are selected, find the following probabilities for the average length of life of the selected batteries. (Round your answers to four decimal places.) (a) The average is between 1,172 and 1,180. (b) The average is greater than 1,188. (c) The average is less than 950.
Fluorescent lighbulbs have lifetimes that follow a normal distribution, with an average life of 1,725 days...
Fluorescent lighbulbs have lifetimes that follow a normal distribution, with an average life of 1,725 days and a standard deviation of 1,462 hours. In the production process the manufacturer draws random samples of 215 lightbulbs and determines the mean lifetime of the sample. What would be the standard deviation, in hours, of the sampling distribution? Std. dev. of sample means (1 decimal place):
After extensive product testing, a battery manufacturer knows that the mean lifetime of its heavy-duty battery...
After extensive product testing, a battery manufacturer knows that the mean lifetime of its heavy-duty battery is normally distributed with a mean of 45 months and a standard deviation of 10 months. (a) The manufacturer currently guarantees free replacement of any battery that fails within 36 months after purchase. What percentage of the batteries should the manufacturer expect to replace? Show your work. Express probabilities in terms of z scores. (b) If the manufacturer wants to replace 10% or fewer...
A certain type of automobile battery is known to last an average of 1160 days with...
A certain type of automobile battery is known to last an average of 1160 days with a standard deviation of 120 days. If 900 of these batteries are selected, find the following probabilities for the average length of life of the selected batteries. (Round your answers to four decimal places.) (a) The average is between 1150 and 1160. 0.0319x (b) The average is greater than 1170 4681x (c) The average is less than 940 0.0336X You may need to use...
27. On a standardized test with a normal distribution, the mean was 64.3 and the standard...
27. On a standardized test with a normal distribution, the mean was 64.3 and the standard deviation was 5.4. What is the best approximation of the percent of scores that fell between 61.6 and 75.1? 28. The mean of a normally distributed set of data is 52 and the standard deviation is 4. Approximately 95% of all the cases will lie between which measures? 29. Battery lifetime is normally distributed for large samples. The mean lifetime is 500 days and...
The mean life of a battery used in a digital clock is 305 days. The lives...
The mean life of a battery used in a digital clock is 305 days. The lives of the batteries follow a normal distribution. The battery was recently modified to last longer. A sample of 20 of the modified batteries had a mean life of 308 days with a standard deviation of 12 days. A hypothesis test is undertaken to determine whether the modification increased the battery life. What is the value of the test statistic for the hypothesis test? In...
The life span of a battery is normally distributed, with a mean of 2000 hours and...
The life span of a battery is normally distributed, with a mean of 2000 hours and a standard deviation of 50 hours. A) What percent of batteries have a life span that is more than 2080 hours? B) Would it be unusual for a battery to have a life span that is more than 2080 hours? [Explain your reasoning.] What percent of batteries have a life span that is more than 2080 hours? Approximately ___% of batteries have a life...
If the lifetime X of a certain kind of automobile battery is normally distributed with mean of 3 years and standard deviation of 1 year, and the manufacturer wishes to guarantee the battery for 2 years, what percentage of the batteries will he have to replace under the guarantee? 5.
9. The service life of automobile tires is modeled by a normal curve; the Mean Time Between Failures (MTBF) is 20,000 miles and the standard deviation is 800 miles. Use Table B in Appendix B (page 868 and 869) to solve these problems. a. Determine the probability that a tire will fail before 22,000 miles. (2.5 point) Answer: b. Determine the probability that a tire will last at least 19,000 miles. (2.5 point) Answer: c. The manufacturer wishes to provide...
A certain type of automobile battery is known to last an average of 1160 days with a standard deviation of 120 days. If 900 of these batteries are selected, find the following probabilities for the average length of life of the selected batteries. (Round your answers to four decimal places.) (a) The average is between 1150 and 1160. 0.0319x (b) The average is greater than 1170 4681x (c) The average is less than 940 0.0336X You may need to use...
27. On a standardized test with a normal distribution, the mean was 64.3 and the standard deviation was 5.4. What is the best approximation of the percent of scores that fell between 61.6 and 75.1? 28. The mean of a normally distributed set of data is 52 and the standard deviation is 4. Approximately 95% of all the cases will lie between which measures? 29. Battery lifetime is normally distributed for large samples. The mean lifetime is 500 days and...
The mean life of a battery used in a digital clock is 305 days. The lives of the batteries follow a normal distribution. The battery was recently modified to last longer. A sample of 20 of the modified batteries had a mean life of 308 days with a standard deviation of 12 days. A hypothesis test is undertaken to determine whether the modification increased the battery life. What is the value of the test statistic for the hypothesis test? In...
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