The upper specification limit for the resistance of coils is 30 Ω. The distribution of coil resistance is known to be normal with a standard deviation of 5 Ω. It is preferred to reject batches that have a mean of 2.3 standard deviations below the upper specification limit no more than 5% of the time.
Also, batches that have a mean of 1 standard deviation below the upper specification should be accepted no more than 8% of the time. Find the parameters of a variable sampling plan and describe its operation.