Wednesday 23 October 2013

Show solutions Fill out the chart below. It is information needed to construct an OC curve and AOQ curve for the following sampling plan: ...

Given: 


Size of lot (N)=1900


Sample Size (n) =125


Acceptance Number (c)=2


Proportion defective (p) can be calculated as :


For np=1.8,


 `p=1.8/125=0.0144`


For np=4.2,


 `p=4.2/125=0.0336`


For np=6.0,


 `p=6.0/125=0.048`


So these values of p completes the Column 1 for p.


Now column 2 can be obtained by multiplying p values with 100.


Now let's fill the column 3 (np) values,


For p=0.0016,


 `np=125*0.0016=0.2`


For p=0.008,


`np=125*0.008=1`


 For p=0.012,


`np=125*0.012=1.5`


For p=0.0224,


`np=125*0.0224=2.8`


For p=0.0416,


`np=125*0.0416=5.2`


...

Given: 


Size of lot (N)=1900


Sample Size (n) =125


Acceptance Number (c)=2


Proportion defective (p) can be calculated as :


For np=1.8,


 `p=1.8/125=0.0144`


For np=4.2,


 `p=4.2/125=0.0336`


For np=6.0,


 `p=6.0/125=0.048`


So these values of p completes the Column 1 for p.


Now column 2 can be obtained by multiplying p values with 100.


Now let's fill the column 3 (np) values,


For p=0.0016,


 `np=125*0.0016=0.2`


For p=0.008,


`np=125*0.008=1`


 For p=0.012,


`np=125*0.012=1.5`


For p=0.0224,


`np=125*0.0224=2.8`


For p=0.0416,


`np=125*0.0416=5.2`


For p=0.0512,


`np=125*0.0512=6.4`


Now let's calculate the Probability of acceptance by the cumulative Poisson formula,


`P_a=sum_(x=0)^c(e^(-np)(np)^x)/(x!)`


We have to calculate P_a for each value of p,


For p=0.016


`P_a=P_0+P_1+P_2`


`=(e^(-0.2)(0.2)^0)/(0!)+(e^(-0.2)(0.2)^1)/(1!)+(e^(-0.2)(0.2)^2)/(2!)`


`=0.818730753+0.163746151+0.016374615`


`=0.998851519`


`=~~0.999`


For p=0.008,


`P_a=(e^(-1)(1)^0)/(0!)+(e^(-1)(1)^1)/(1!)+(e^(-1)(1)^2)/(2!)`


`=0.367879441+0.367879441+0.183939721` 


`=0.919698603`


`=~~0.92` 


For p=0.012,


`P_a=(e^(-1.5)(1.5)^0)/(0!)+(e^(-1.5)(1.5)^1)/(1!)+(e^(-1.5)(1.5)^2)/(2!)`


`=0.22313016+0.33469524+0.25102143`


`=0.808846831`


`=~~0.809`


Similarly we can calculate P_a for all values of p, which are shown in the attached image.


Now let' calculate AOQ,


`AOQ=(P_a*p)(N-n)/N`


If `n/N<=0.1`


Then, AOQ `=P_a*p`


Now let's calculate AOQ,


For p=0.0016,


`AOQ=0.0016*0.999=0.0015984`


For p=0.008,


`AOQ=0.008*0.92=0.00736`


Similarly we can calculate AOQ, for other values of p.


Please refer to the attached image, where all calculations are shown.


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