A newly designed phone battery, when fully charged, is supposed to last 48 hours with a tolerance limit of plus or minus 30 minutes under normal use. The current production process produces batteries that on average last 47.5 hours before requiring a recharge with a standard deviation of 15 minutes.
a. Compute Cpk and Cp. Is this process capable? Explain your answer.
b. Changes to production process were implemented and the batteries produced now last on average 47.8 hours before requiring recharge with a standard deviation of 15 minutes hours.
Is this modified process capable? Explain your answer.
c. If the process is still not capable what further action would you recommend to make the process capable?