Light globes produced by a manufacturing company have had a life expectancy of 1350 hours. Because of an improved production process, the company believes that there has been an increase in the life expectancy of its light globes. A sample of 49 globes showed an average life of 1510 hours. From past information, it is known that the standard deviation of the population is 385 hours. Test to determine whether there has been an increase in the life expectancy of the light globes. What is the value of the calculated test statistic and what conclusion can be made at the 1% level of significance?

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