A company producing LED bulbs finds that mean life span of the population of its bulbsis 2000 hours with a standard derivation of 150 hours. A sample of 100 bulbs randomly chosenis found to have the mean life span of 1950 hours. Test, at 5% level of significance, whether themean life span of the bulbs is significantly different from 2000 hours.

Answered: Image /qna-images/answer/174a1018-cb11-408e-acba-370ef150a5e2.jpg

Answered: A company producing LED bulbs finds…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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Assume that adults have IQ scores that are normally distributed with a mean of 100.7 and a standard deviation 18.9. Find the first quartile, which is the IQ score separating the bottom 25% from the top to 75%
in a test of a lifelong brand of tires , a survey revealed that the mean life was 35,000 mikes and the standard deviation was 7083 mikes. if the shape of the population distribution is known to be normal, approximately what percentage of the tires lasts less than 20834 miles ?
The distribution for the time a patient of a medical center spends waiting for an appointment is normal with mean of 35 minutes and standard deviation of 12 minutes. What proportion of patients will wait more than 47 minutes for an appointment?
Your company markets a computerized device for detecting high blood pressure. The device measures an individual's blood pressure once per hour at a randomly selected time throughout a 12-hour period. Then it calculates the mean systolic (top number) pressure for the sample of measurements. Based on the sample results, the device determines whether there is significant evidence that the individual's actual mean systolic pressure is greater than 139. If so, it recommends that the person seek medical attention. The null and alternative hypotheses are given. H0: μ = 139 Ha: μ > 139 (a) Describe a Type I error in the context of this problem. 1. The machine tells someone that they have high systolic blood pressure when, in fact, they do. 2. The machine doesn't tell someone that they have high systolic blood pressure, when, in fact, they do. 3. The machine doesn't tell someone that they have high systolic blood pressure when, in fact, they do not. 4. The machine tells…
A certain prescription medicine is supposed to contain an average of 250 parts per million (ppm) of a certain chemical. If the concentration is higher than this, the drug may cause harmful side effects; if it is lower, the drug may be ineffective. The manufacturer runs a check to see if the mean concentration in a large shipment conforms to the target level of 250 ppm or not. A simple random sample of 100 portions is tested, and the sample mean concentration is found to be 247 ppm. The sample concentration standard deviation is s = 12 ppm. What are the appropriate null and alternative hypotheses? Group of answer choices H 0: x̄ = 250 vs. H a: x̄ < 250 H 0: x̄ = 250 vs. H a: x̄ ≠ 250 H 0: x̄ = 250 vs. H a: x̄ > 250 H 0: μ = 250 vs. H a:μ < 250 H 0: μ = 250 vs. H a: μ ≠ 250 H 0: μ = 250 vs. H a: μ > 250
A consumer group plans a comparative study of the mean life of four different brands of batteries. Ten batteries of each brand will be randomly selected and the time until the energy level falls below a pre-specified level is measured.
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
The mean number of hours students studied each day was 4 with a standard deviation of 1.5 hours. The distribution was normal. What proportion of students studied 6 hours or more per day? What proportion of students studied 2 hours or more per day? How many hours would an individual at the 60th percentile rank study?
Low‑density lipoprotein, or LDL, is the main source of cholesterol buildup and blockage in the arteries. This is why LDL is known as "bad cholesterol." LDL is measured in milligrams per deciliter of blood, or mg/dL. In a population of adults at risk for cardiovascular problems, the distribution of LDL levels is normal, with a mean of 123123 mg/dL and a standard deviation of 4141 mg/dL. If an individual's LDL is at least 11 standard deviation or more above the mean, he or she will be monitored carefully by a doctor. What percentage of individuals from this population will have LDL levels 11 or more standard deviations above the mean? Use the 6868–9595–99.799.7 rule. (Enter your exact answer as a whole number.)
A sociologist found that in a sample of 45 retired men, the average number of jobs they had during theirlifetimes was 7.2. The population standard deviation is 2.3(a) Find the best point estimate of the mean.The best point estimate of the mean is
A sample of 75 will be drawn from a population of test takers with a mean of 150 and standard deviation 9. Find the 85th percentile.
A study of commuting times reports the travel times to work of a random sample of 1068 employed adults in Chicago. The mean is x = 54.0 minutes and the standard deviation is s = 60.9 minutes. What is the standard error of the mean?

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