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Hypothesis

A light bulb manufacturer advertises that the average life for their light bulbs is 800 hours. A random sample of 15 of their light bulbs resulted in the following data, in hours;
990 841 953 612 727 800 686 594
835 897 943 791 750 667 723

Assume that the bulb life is normally distributed. At the 10% significance level, do the data provide evidence that the mean life for the company's light bulbs differs from the advertised mean?

Solution Preview

Let X denotes the lif of a bulb.
<br>SUM(X) = 11809 hour
<br><X> = 11809/15 = 787.27 hour
<br>SUM(X^2) = 9508977
<br>n = 15 (sample size)
<br>hence,
<br>s^2 = ...

Solution Summary

A light bulb manufacturer advertises that the average life for their light bulbs is 800 hours. A random sample of 15 of their light bulbs resulted in the following data, in hours;
990 841 953 612 727 800 686 594
835 897 943 791 750 667 723

Assume that the bulb life is normally distributed. At the 10% significance level, do the data provide evidence that the mean life for the company's light bulbs differs from the advertised mean?

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