50 confidence interval

90% confidence interval of a population mean(μ) worked out on a sample size of 50 is, 50 < μ < 56. What is the likely 90% confidence interval of the mean of the same population worked out on a sample size of 100? => 25 < &mu..

A recent study of 50 people in a city found that 70% of the people have less than average incomes for the city. How many people should be surveyed to estimate the true proportion of people having an income of less than average with a 99% confidence interval 4% wide? =>..

A manufacturer of incandescent bulbs claims that the average life time of a bulb is 1,000 hours with a standard deviation of 1.6 hours. The inspection department selected a random sample of 42 incandescent bulbs and found their average life time as 998.50 hours. At α = 0.1, can the ..

The formula for the confidence interval for a standard deviation is ________ . => III or II or IV or I..

When a 95% confidence interval is calculated instead of a 90% confidence interval with the same sample, the maximum error of estimate will be _____ . => either smaller or larger depending on sample size or the same or smaller or larger..

To calculate the confidence interval for variance or standard deviation, a statistical distribution called ______ is needed. => chi-square distribution or binomial distribution or poisson distribution or multinomial distribution..

The life expectancy (years) at birth of a random sample of 20 countries is shown here. Find the 99% confidence interval for the standard deviation. Assume that the variable is normally distributed. 77 67 76 69 60 57 59 55 57 53 54 50 51 49 50 49 72 69 50..

A television channel conducted a survey of 90 adults and found that 54 regularly watch television at home. Find a 90% confidence interval of the true proportion of adults who watch television regularly. => 59.6% < p < 60.4% or 50% < p < 60% or 54.8% < p ..

A sample of the reading scores of 35 sixth graders has a mean of 82. If the 95% confidence interval for the population mean of the reading scores of all fifth graders is between 77 and 87, then which among the following choices represents the 99% confidence interv..

A survey of 120 families showed that at least 78 had a computer at home. Find the 99% confidence interval of the true proportion of families who own a home computer. => 64.5% < p < 65.5% or 5.38% < p < 7.62% or 53.8% < p < 76.2% or 60.6% < p < 69.4%..