Defects in computer hard-drives will usually render the entire computer worthless.For a particular model, the percent defective in the past has been 1%.If a sample size of 400 is taken, what would the 95.5% lower control chart limit be?
A)0.00995
B)0.00005
C)0.00000
D)0.01000

Question

Quizplus · Accepted Answer

The lower control chart limit can be calculated using the formula:
LCL = p - 1.96*sqrt(p(1-p)/n)
where p is the percent defective, n is the sample size, and 1.96 is the z-value for the 95.5% confidence level.
Substituting the values given:
LCL = 0.01 - 1.96*sqrt(0.01*0.99/400)
LCL = 0.00005
Therefore, the answer is B.

Defects in Computer Hard-Drives Will Usually Render the Entire Computer