i need help with HW probelm 15,16,17

sam Tamples of size four were taken from a process, and their weights measured. The sample averages and If If 3-sigma control limits are used, calculat - tha ln.............. timit nnd nnner control limit. 16) Plot points on the control chart with the mean and the upper and lower control limits labeled. 17) Is this process in control? Why or why not