Question

Asked Oct 18, 2019

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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

117 hours. A random sample of 81 light bulbs indicated a sample mean life of 370 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 336.5 hours to an upper limit of 403.5 hours.

(Round to one decimal place as needed.)

*b. Do you think that the manufacturer has the right to state that the lightbulbs have a mean life of 420 hours? Explain.*

117 hours. A random sample of 81 light bulbs indicated a sample mean life of 370 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 336.5 hours to an upper limit of 403.5 hours.

(Round to one decimal place as needed.)

Based on the sample data, the manufacturer** [does not have / has]** the right to state that the lightbulbs have a mean life of 420 hours. A mean of 420 hours is ** [less than 2/more than 3]**

standard errors**[above/ below]** the sample mean, so it is [**likely/ highly unlikely]**

that the lightbulbs have a mean life of 420 hours.

standard errors

that the lightbulbs have a mean life of 420 hours.

Step 1

From the given information,

Sample mean life of bulbs = 370 hrs.

Populat

From the given information,

Sample mean life of bulbs = 370 hrs.

Population standard deviation(σ) = 117 hrs.

Sample size = 81,

ion standard deviation(σ) = 117 hrs.

Sample size = 81,

Step 2

a)

A 99% confidence interval estimate for the population mean life of light bulbs is given as:

Step 3

Therefore, the 99% confidence interval of the me...

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