At a certain manufacturing plant , a machine produces ball bearings that should have a diameter a certain of 1 500 mm If the machine produces ball bearings that are either too small or too large , the all bearings must be scrapped Every hour , a quality control manager takes a random sample of 36 ball bearings to test to see if the process is " out of control " ( Le . to test to see if the average diameter differs from o 1500 mm ) . The standard deviation of the process is not known At a Of level of significance , use Excel to test whether the process is " out of control . Is it a 1 - tail or 2 - tail test Q2 What is the Sample Sted dev ? What is T - critical 1 .354 Q What is T -stat ? D.456 25 Use Excel's T functions to find P- value 1.471 should you reject the Null or not ? 0. 468 0.513 0.521 D. 417 0. 421 0 . 416 0418 0558 0411 1 346 0.319