Answer:
<em>a)95% confidence intervals for the population mean of light bulbs in this batch</em>
(325.5 ,374.5)
b)
<em>The calculated value Z = 4 > 1.96 at 0.05 level of significance</em>
<em>Null hypothesis is rejected </em>
<em>The manufacturer has not right to take the average life of the light bulbs is 400 hours.</em>
Step-by-step explanation:
Given sample size n = 64
Given mean of the sample x⁻ = 350
Standard deviation of the Population σ = 100 hours
The tabulated value Z₀.₉₅ = 1.96
<em>95% confidence intervals for the population mean of light bulbs in this batch</em>
<em></em><em></em>
<em></em><em></em>
(325.5 ,374.5)
b)
<u><em>Explanation</em></u>:-
Given mean of the Population μ = 400
Given sample size n = 64
Given mean of the sample x⁻ = 350
Standard deviation of the Population σ = 100 hours
<u><em>Null hypothesis</em></u> : H₀:The manufacturer has right to take the average life of the light bulbs is 400 hours.
μ = 400
<u><em>Alternative Hypothesis: H₁:</em></u> μ ≠400
<u><em>The test statistic </em></u>
|Z| = |-4|
The tabulated value Z₀.₉₅ = 1.96
The calculated value Z = 4 > 1.96 at 0.05 level of significance
Null hypothesis is rejected.
<u><em>Conclusion:</em></u>-
The manufacturer has not right to take the average life of the light bulbs is 400 hours.