construction company has just constructed 150 new apartments. An external inspector is hired to do the final checking before they are given way to prospective customers. Inspector at random selects 8 apartments and and counts how many defects are in each one them. He finds 7,3, 2, 1, 2, 5, 4, 4 defects. What will be Upper Control Limit for a C chart

Given - construction company has just constructed 150 new apartments. An external inspector is hired to do the final checking before they are given way to prospective customers. Inspector at random selects 8 apartments and and counts how many defects are in each one them. He finds 7,3, 2, 1, 2, 5, 4, 4 defects.

To find - What will be Upper Control Limit for a C chart ?

Proof -

Upper Control Limit for a c-chart = c bar + 3(square root of c bar)

Now,

c bar = [tex]\frac{7+3+2+1+2+5+4+4}{8}[/tex] = 3.5

∴ we get

Upper Control Limit for a c-chart = 3.5 + 3(square root of 3.5)

= 3.5 + (1.87)

= 3.5 + 5.61

= 9.1

⇒Upper Control Limit for a c-chart = 9.1