trol manager at a light bulb factory needs to estimate the mean life of a large shipment of light bulbs. The standard deviation is 91 hours. A random sample of 49 light bulbs indicated a sample mean life of 360hours 1. Construct a 95​% confidence interval estimate for the population mean life of light bulbs in this shipment (Round to one decimal place and show your equation) 2. Suppose that the standard deviation changes to 84 hours, construct a 95% confidence interval estimate just like in part 1 and show your equation again.

Definition Definition Measure of central tendency that is the average of a given data set. The mean value is evaluated as the quotient of the sum of all observations by the sample size. The mean, in contrast to a median, is affected by extreme values. Very large or very small values can distract the mean from the center of the data. Arithmetic mean: The most common type of mean is the arithmetic mean. It is evaluated using the formula: μ = 1 N ∑ i = 1 N x i Other types of means are the geometric mean, logarithmic mean, and harmonic mean. Geometric mean: The nth root of the product of n observations from a data set is defined as the geometric mean of the set: G = x 1 x 2 ... x n n Logarithmic mean: The difference of the natural logarithms of the two numbers, divided by the difference between the numbers is the logarithmic mean of the two numbers. The logarithmic mean is used particularly in heat transfer and mass transfer. ln x 2 − ln x 1 x 2 − x 1 Harmonic mean: The inverse of the arithmetic mean of the inverses of all the numbers in a data set is the harmonic mean of the data. 1 1 x 1 + 1 x 2 + ...