Answer to Question #35707 in Statistics and Probability for Tammy Tung

Question

1.The new Twinkle bulb has a standard deviation 45 hours. A random sample of 60 light bulbs is selected from inventory. The sample mean was found to be 500 hours.
Construct 90%, 95% and 99% confidence intervals for the mean life, of all Twinkle bulbs. Round to the nearest three decimals.
2. A standard placement test has a mean of 125 and a standard deviation of 15. Determine the minimum sample size if we want to be 95% certain that we are within 3 points of the true mean.
3. An experimental egg farm is raising chickens to produce low cholesterol eggs. A lab tested 20 randomly selected eggs and found that the mean amount of cholesterol was 180 mg. The sample standard deviation was found to be s = 25.0 mg on this group. Assume that the population is normally distributed. Find 90%, 95% and 99% confidence intervals for the mean cholesterol content for all experimental eggs. Assume that the population is normally distributed. Round to the nearest three decimals.
4.The new Twinkle bulb is being developed to last more than 1000 hours. A random sample of 120 of these new bulbs is selected from the production line. It was found that 90 lasted more than 1000 hours. Construct 90%, 95% and 99% confidence intervals for the population proportion “p” of all Twinkle bulbs. Round to the nearest three decimals