What is the value of Cpm?

• A. (C_{pm}= frac{USL+LSl}{6 } )
• B. (C_{pm}= frac{USL-LSl}{6 } )
• C. (C_{pm}= frac{USL+LSl}{6 } )
• D. (C_{pm}= frac{USL-LSl}{6 } )