A manufacturer claims that the mean lifetime, u, of its light bulbs is 45 months. The standard deviation of these lifetimes is 4 months. Thirty bulbs are seled at random, and their mean lifetime is found to be 44 months. Assume that the population is normally distributed. Can we conclude, at the 0.01 level of significance, that the mean lifetime of light bulbs made by this manufacturer differs from 45 months?

A manufacturer claims that the mean lifetime, u, of its light bulbs is 45 months. The standard deviation of these lifetimes is 4 months. Thirty bulbs are seled at random, and their mean lifetime is found to be 44 months. Assume that the population is normally distributed. Can we conclude, at the 0.01 level of significance, that the mean lifetime of light bulbs made by this manufacturer differs from 45 months?

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

Suppose a researcher wants to test if the average diastolic blood pressure in Irish-Americans is different than the average diastolic blood pressure in the general population. Note that the average diastolic blood pressure in the general population is 70 mmHG. The researcher recruits 30 Irish-Americans into this particular study and then measures each of their diastolic blood pressures (mmHG). The population of this sample has a standard deviation equal to 3.0. What is the two-sided alternative hypothesis? (in words) Group of answer choices The mean is different than 70 The mean is different than 73 The mean is greater than 70 The mean is greater than 73
Suppose that the volume of sound generated by heavy machinery in a factory is normally distributed, with a mean of 50 dB and a standard deviation of 10 dB. If measurements are taken twice an hour during an eight hour period, 20% of the sample average sound volumes will be above what value?"
Suppose babies born after a gestation period of 32 to 35 weeks have a mean weight of 2600 grams and a standard deviation of 600 grams while babies born after a gestation period of 40 weeks have a mean weight of 2800 grams and a standard deviation of 390 grams. If a 32-week gestation period baby weighs 2150 grams and a 40-week gestation period baby weighs 2350 grams, find the corresponding z-scores. Which baby weighs less relative to the gestation period?
A random sample of 10 subjects have weights with a standard deviation of 11.9848 kg . What is the variance of their weights ? Be sure to include the appropriate units with the result .
Suppose babies born after a gestation period of 32 to 35 weeks have a mean weight of 2800 grams and a standard deviation of 900 grams while babies born after a gestation period of 40 weeks have mean weight of 3400 grams and a standard deviation of 445 grams. If a 33-week gestation period baby weighs 2625 grams and a 41-week gestation period baby weighs 3225 grams, find the corresponding z-scores. Which baby weighs less relative to the gestation period? Find the corresponding z-scores. Which baby weighs relatively less? Select the correct choice below and fill in the answer boxes to complete your choice. (Round to two decimal places as needed.) OA. The baby born in week 33 weighs relatively less since its z-score, OB. The baby born in week 33 weighs relatively less since its z-score, OC. The baby born in week 41 weighs relatively less since its z-score, OD. The baby born in week 41 weighs relatively less since its z-score, is smaller than the z-score of is larger than the z-score of is…
A psychologist obtains a random sample of 30 mothers in the first trimester of their pregnancy. The mothers are asked to play Mozart in the house at least 45 minutes each day until they give birth. We know that IQs are normally distributed with a mean of 100. A few years after their births the children were given an IQ test and the IQs of the 30 children in the study resulted in a sample mean of 104.2. Assume the population standard deviation for IQ of children is 15. Is there evidence that the children who listen to Mozart for at least 45 minutes each day during pregnancy have higher IQs at the 0.05 level of significance? Step 1: Define the parameter & setup the testStep 2: State the Level of SignificanceStep 3: Find the value of the Test StatisticsStep 4: Find P-Value OR Find Critical ValueStep 5: State Conclusion and why
Suppose that heights of 10-year-old boys in the US vary according to a normal distribution with mean of 138 cm and standard deviation of 7. Compute the Z-score for a boy with height of 150 cm and find the correct interpretations. a. Boy's height is 0.71 standard deviation lower the national average b. Boy's height is 1.71 standard deviation above the national average c. Boy's height is 1.71 standard deviation lower than the national average d. Boy's height is 2.71 standard deviation above the national average
In a school district, all sixth grade students take the same standardized test. The superintendant of the school district takes a random sample of 3030 scores from all of the students who took the test. She sees that the mean score is 169169 with a standard deviation of 7.06747.0674. The superintendant wants to know if the standard deviation has changed this year. Previously, the population standard deviation was 1313. Is there evidence that the standard deviation of test scores has decreased at the α=0.005α=0.005 level? Assume the population is normally distributed. Step 1 of 5: State the null and alternative hypotheses. Round to four decimal places when necessary. Step 2 of 5: Determine the critical value(s) of the test statistic. If the test is two-tailed, separate the values with a comma. Round your answer to three decimal places. Step 3 of 5: Determine the value of the test statistic. Round your answer to three decimal places. Step 4 of 5: Make the…
Assume that weights of adult females are normally distributed with a mean of 77 kg and a standard deviation of 22 kg. What percentage of individual adult females have weights between 71 kg and 83 kg? If samples of 100 adult females are randomly selected and the mean weight is computed for each sample, what percentage of the sample means are between 71 kg and 83 kg?
An Internet provider has analyzed the amount of time it’s customers are online per session. It found that the distribution of connect times has a mean a 43 minutes and a standard deviation of 10 minutes. For this distribution find the raw score that corresponds to a z score of 1.1
During the busy season, it is important for the shipping manager at ShipMundo to be able to estimate the time it takes the loading crew to load a truck. The shipping manager has found that she can model the load times using a normal distribution with a mean of 152 minutes and a standard deviation of 15 minutes. Use this table or the ALEKS calculator to find the percentage of load times between 116 minutes and 149 minutes according to the model. For your intermediate computations, use four or more decimal places. Give your final answer to two decimal places (for example 98.23%).
Assume all populations are normally distributed. A travel analyst claims that the mean price of a round trip flight from New York City to Los Angeles is less than $507. In a random sample of 55 round trip flights from NYC to LA, the mean price is $502. Assume the population standard deviation is $111. At α = 0.05, is there enough evidence to support the travel analyst’s claim?