A lightbulb manufacturer produces 1.4 million light bulbs a year at a California

Question

A lightbulb manufacturer produces 1.4 million light bulbs a year at a California plant. To test for quality, she uses two different methods to measure the lifetime of a 100 lightbulbs. Using the first method the avg. lifetime is 810 hrs and the standard deviation is 30 hrs. Using the second method the avg. lifetime is 830 hrs and the standard deviation is 95 hrs. Assume that the "true" lifetime of these bulbs is 829 hrs. a. Does the set of 100 bulbs represent a sample or a population? b. Which method is more precise? Explain. c. Which method is more accurate? Explain.

Explanation / Answer

Answer:

a).

The set of 100 bulbs represent a sample.

b).

Precision is how close the measured values are to each other.

First method is more precise because its standard deviation is smaller.

c).

Accuracy is how close a measured value is to the actual (true) value.

Second method is more accurate because its average 830 hrs is closer to true value of 829 hrs.

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