I understand how to find A and B (they are correct), but I can not figure out the errors I am making in finding C. Thank you for your help.

Refer to Table S6.1 - Factors for Computing_Control Chart Limits (3 sigma). for this problem. Auto pistons at Wemming Chung's plant in Shanghai are produced in a forging process, and the diameter is a critical factor that must be controlled. From sample sizes of 10 pistons produced each day, the mean and the range of this diameter have been as follows: a) What is the value of x ? x=mm(roundyourresponsetotwodecimalplaces). b) What is the value of R ? R=4.48mm(roundyourresponsetotwodecimalplaces). c) What are the UCL and LCL using 3-sigma? Upper Control Limit (UCLx)=mm (round your response to two decimal places)