Question

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. 0.09550
C. 0.00000
D. 0.01000
E. 0.00005

Answer 1

Answer:

E. 0.00005

Explanation:

Here Average Fraction defective, p = 1% = 0.01

95.5% deviation means 2x

x = sqrt{x*(1 - x)/n)}

  = sqrt{0.01*(1 - 0.01)/100}

  = 0.00995

LCL = p - 2x

      = 0.01 - 0.00995

      = 0.00005

Therefore, The 95.5% lower control chart limit be 0.00005