A transmitter has failure rates as presented in Table 10-2. A proof test is performed every 5 years during a process shutdown. The proof test coverage is 92% and MTTRDD is 168 hours. After any replacement transmitters are installed, they can be tested. At the end of the fourth 5-year interval, the process is shut down and overhauled. Thus, the mission time is 20 years. The site is evaluated to be SSI 2. What is the PFDavg for this sensor element? Is this significantly different than the result in Example 10-3, even though the MTTRDD has increased from 96 to 168 hours?