Practice $3$

Question:

The following data $($in ohms$)$ are the resistance of resistors made on an automated machine.

$\backslash$table$[[,$Resistance of Resistors $($in Ohms$),],[$Sample$,$Obs $1,$Obs $2,$Obs $3,$Obs $4],[1,1,010,991,985,986],[2,995,996,1,009,994],[3,990,1,003,1,015,1,008],[4,1,015,1,020,1,009,998],[5,1,013,1,019,1,005,993],[6,994,1,001,994,1,005],[7,989,992,982,1,020],[8,1,001,986,996,996],[9,1,006,989,1,005,1,007],[10,992,1,007,1,006,979]]$

a$.$ Develop sample mean and sample range control charts for resistance of resistors using the samples. $[2$ marks$]$

Note: Use a graph paper.

b$.$ Is the process in control? $[1$ mark$]$

c$.$ Use the control charts developed in part a to decide if the ${11}^{th}$ sample $($given below$)$ indicates an out$-$of$-$control situation. $[2$ marks$]$

$\backslash$table$[[$Sample$,$Obs $1,$Obs $2,$Obs $3,$Obs $4],[11,996,1,006,997,989]]$