The quality control manager at a light bulb factory needs to estimate the mean life of a large shipment of light bulbs. The standard deviation is 98 hours. A random sample of 49 light bulbs indicated a sample mean life of 360 hours. Complete parts(a) through(d) below.

a. Construct a 99% confidence interval estimate for the population mean life of light bulbs in this shipment.

The 99% confidence interval estimate is from a lower limit of

323.8

323.8 hours to an upper limit of

396.1

396.1 hours.

(Round to one decimal place asneeded.)

b. Do you think that the manufacturer has the right to state that the lightbulbs have a mean life of 410 hours? Explain.

Based on the sampledata, the manufacturer

the right to state that the lightbulbs have a mean life of 410 hours. A mean of 410 hours is

standard errors

the samplemean, so it is

that the lightbulbs have a mean life of 410 hours.