3. The quality control manager at a light bulb factory needs to determine whether the average life of a large shipment of light bulbs is equal to the specified value of 475 hours. The process standard deviation is known to be 200 hours. A random sample of 64 light bulbs indicates a sample mean life of 480 hours. At the 0.01 level of significance, is there evidence that the mean life is greater than 475 hours? a. State the null and alternative hypothesis b. Is it a two tail test or one-tail test? C. Write the test Statistic (Z or T)? d State the critical value (S) e. State the conclusion (Reject Ho or Do not reject Ho) f. State the conclusion as a relationship to the problem. 4. A manager of the credit department for an oil company would like to determine whether the average monthly balance of credit card holders is equal to $75. An auditor selects a random sample of 100 accounts and finds that the average owed is $83 40 with a sample standard deviation of $23.65. If you wanted to test whether the auditor should conclude that there is evidence that the average balance is different from $75? a. State the null and alternative hypothesis b. Is it a two tail test or one-tail test? C. Write the test Statistic (Z or T)? d State the critical value (S) e. State the conclusion (Reject Ho or Do not reject Ho) f. State the conclusion as a relationship to the