random samples

The population survey in 2001 stated that 37% of urban workers held multiple jobs in order to earn extra money. From a random sample of 200 urban workers taken, it was found that 70 of them held multiple jobs. Find the p -value for the test. Does the sample proportion ..

The average annual salary in a district is $30,000. Assuming that the salaries were normally distributed for a certain group of wage earners with a standard deviation of $5,000, what is the probability that for a randomly selected sample of 70 earners the mean salary falls below..

A company makes wooden wardrobes having a standard height of 55 in., with a standard deviation of 2.5 in. In a random sample of 23 wardrobes, 6 wardrobes measured 58.5 in., 8 wardrobes measured 53.8 in. and 9 wardrobes measured 56 in.. Find the 95% confidence interval. => The in..

Internet services reported that 33% of the secondary school principals use internet email more than once a day either in home or school. From a random sample of 120 secondary school principals, it was found that 42 use internet email more than once a day. Is there enough evidenc..

A manufacturer reported that 95% of electronic components manufactured by them are free from defects. From a random sample of 80 components, 5 had defects. Find the p -value for the test. Is there enough evidence to reject the manufacturer's report at α = 0.01? => 0.305; y..

Three different companies produce a particular type of electronic component. Random samples of components are selected from each company. Components are put into actual use until they fail and the life time of the components noted are as shown. At α = 0.10, find the F test..

A manufacturer of bulbs claims that the variance of the span of life of the bulbs is 320 hours. The inspection department selected a random sample of 15 bulbs and found the variance as 210 hours. Find the chi-square test value. At α = 0.05, is there enough evidence to reje..

A survey reported that 38% of Americans go to the supermarket during noon to 5 p.m. In a random sample of 130 Americans, it was found that 47 responded the same. Find the p -value for the test. Is the survey report correct at α = 0.05? => 0.3192; no or 0.6384; no or 0.6384..

A survey suggests that 90% of the chief executives of the largest companies in the United States are of above average height. From a random sample of 140 executives it was observed that 119 are of above average height. Find the p -value for the test. Is there enough evidence to ..

The standard deviation of the annual income of a random sample of 20 doctors in U.S. having one to two years experience is $5900. Test the hypothesis that the standard deviation of the population is more than $5,400 a year at α = 0.05. Also write the chi-square test value...