How is the PFDAVG calculated for a single transmitter tested on-line every 3 months, given a dangerous undetected failure rate of 1.44 x 10 -7 f/hr?

• A. 0.0016
• B. 0.00016
• C. 0.000315
• D. 2.16 x 10 -7

Answer: (B)

To calculate the Probability of Failure on Demand Average (PFDAVG) for a single transmitter tested on-line every three months, one must first understand the relationship between the failure rate and the testing interval.

In this case, the dangerous undetected failure rate is given as 1.44 x 10^-7 failures per hour. The testing interval is 3 months, which can be converted into hours for consistency. There are roughly 2,190 hours in 3 months (assuming a month is approximately 730 hours).

The PFDAVG can be calculated using the formula:

PFDAVG = (Failure rate * Testing interval) / (1 + (Failure rate * Testing interval))

First, we calculate the Testing interval in hours:

Testing interval = 3 months * 730 hours/month = 2,190 hours.

Next, we compute the numerator:

Failure rate * Testing interval = (1.44 x 10^-7 f/hr) * (2,190 hr) = 3.1552 x 10^-4.

Now, plug this into the PFDAVG formula:

PFDAVG = (3.1552 x 10^-4) / (1 + (3.1552 x 10^-4