Good day,

I hope you are well.

I would please like some assistance and an explanation on each of the following questions about constructing a 95% confidence interval individually.

I look forward to your reply.

ing to another question will save this response. >> Question 4 10 points Save Answer Certain medical costs are approximately normally distributed. A random sample of 250 operations showed a mean of R374 and a standard deviation of R56.25 Construct a 90% confidence interval for the mean of these costs. Give the lower limit. 367.0271 368.1478 364.8356 383.1644 Question 5 10 points Save Answer A random sample of 8 cigarettes of a certain brand has an average nicotine content of 2.6 milligram and standard deviation of 0.9 milligrams. Construct a 90% confidence interval for the true average nicotine content of this brand of cigarettes, assuming the distribution of nicotine content to be normal. Give the upper limit. O 3.203 O 3.3525 O 3.7134 O 1.4866 > Question 7 10 points Save Answer The heights of a random sample of 50 Hereford calves at birth showed a mean of 71 cm and a standard deviation of 6.7 cm. Construct a 90% confidence interval for the mean height of all Hereford calves at birth. Give the lower limit. O 68.5592 69.4413 69.1429 O 73.4408 Question 8 10 points Save Answer A random sample of 8 cigarettes of a certain brand has an average nicotine content of 2.6 milligram and standard deviation of 0.9 milligrams. Construct a 90% confidence interval for the true average nicotine content of this brand of cigarettes, assuming the distribution of nicotine content to be normal. Give the lower limit. O 1.997 O 1.8475 O 1.4866 O 3.3525 Question 9 10 points Save Answer Light bulbs supplied by a certain company have a length life that is approximately normally distributed, with the standard deviation of 40 hours. If a random sample of 36 bulbs has an average life of 780 hours, find a 90% confidence interval for the population mean of all bulbs supplied by this company. Give the lower limit. O 766.9333 O 762.8266 O 769.0333 790.9667