The Robin Hood Bank has noticed an apparent recent decline in the daily demand deposits. The average daily demand deposit balance has been running at $109 million with an average range of $15 million over the past year. The demand deposits for the past six days have been 110, 102, 96, 87, 115, and 106.
a. What are the CL, UCL, and LCL for the x and R charts based on a sample size of 6?
b. Compute an average and range for the past six days. Do the figures for the past six days suggest a change in the average or range from the past year?