A new light bulb is being considered for use in an office It is decided that the new bulb will be used only if it has a mean lifetime of more than 500 hours. A random sample of 40 bulbs is selected and placed on life test. The mean and standard deviation are found to be 505 hours and 18 hours, respectively. Perform the appropriate test of hypothesis to determine whether the new bulb should be used. Use a 0.01 level of significance.

Question

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The Answer is The hypotheses to be tested are

The hypotheses to be tested are . The test statistic is = (505 - 500)/(18/ ) = 1.76. Since -2.33 < z < 2.33, we fail to reject the null hypothesis. We conclude that the true average lifetime of the bulb is not significantly larger than 500 (i.e., do not use this bulb.)

. The test statistic is The hypotheses to be tested are . The test statistic is = (505 - 500)/(18/ ) = 1.76. Since -2.33 < z < 2.33, we fail to reject the null hypothesis. We conclude that the true average lifetime of the bulb is not significantly larger than 500 (i.e., do not use this bulb.)

= (505 - 500)/(18/ The hypotheses to be tested are . The test statistic is = (505 - 500)/(18/ ) = 1.76. Since -2.33 < z < 2.33, we fail to reject the null hypothesis. We conclude that the true average lifetime of the bulb is not significantly larger than 500 (i.e., do not use this bulb.)

) = 1.76. Since -2.33 < z < 2.33, we fail to reject the null hypothesis. We conclude that the true average lifetime of the bulb is not significantly larger than 500 (i.e., do not use this bulb.)

A New Light Bulb Is Being Considered for Use in an Office