# 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?

© BrainMass Inc. brainmass.com June 3, 2020, 5:06 pm ad1c9bdddfhttps://brainmass.com/statistics/normal-distribution/hypothesis-14683

#### 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?