this is a Btech subject

3 a) Consider a cropping press on which bars are to be cut continuously to a length of 12cm. A random sample of 5 bars is taken from each hours production and for each sample, the mean and range are calculated as shown in table below. Construct and R charts and examine whether the process is under control and state your recommendations. Sample Range R (size n -5) Mean & 12.004 0.008 12,002 0.007 11,992 0.010 11.993 0.004 12.000 0.005 12.003 0.015 11.996 0.012 12.003 0.007 12.003 0.009 12.000 0.010 11.998 0.005 11.996 0.014 13 12.001 0.010 14 12.000 0.011 b) Explain the control charts for variables.(