SOLUTION: 2. The new Twinkle bulb has a standard deviation hours. A random sample of 77 light bulbs is selected from inventory. The sample mean was found to be 492 hours.
a. Find the ma
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a. Find the ma
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Question 232098: 2. The new Twinkle bulb has a standard deviation hours. A random sample of 77 light bulbs is selected from inventory. The sample mean was found to be 492 hours.
a. Find the margin of error E for a 90% confidence interval. (5 points)
Round your answer to the nearest hundredths. (References:
definition of margin of error on page 312 and example 2 on
page 312).
b. Construct a 90% confidence interval for the mean life, of all Twinkle
bulbs. (References: example 5 page 315, end of section exercises 51 - 56 on pages 319 - 320) (5 points)
3. A standard placement test has a mean of 105 and a standard deviation of = 13. Determine the minimum sample size if we want to be 99% certain that we are within 3 points of the true mean
4. An experimental egg farm is raising chickens to produce low cholesterol eggs. A lab tested 12 randomly selected eggs and found that the mean amount of cholesterol was 186 mg. The sample standard deviation was found to be s = 19.0 mg on this group. Assume that the population is normally distributed. (References: example 2 and 3 pages 327 - 328, end of section exercises 5 - 16 on pages 330 - 331)
a. Find the margin of error for a 95% confidence interval. Round your answer to the nearest tenths. (2.5 points)
b. Find a 95% confidence interval for the mean cholesterol content for all experimental eggs. Assume that the population is normally distributed. (2.5 points)
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Cheers,
Stan H.
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