The Power of a Single Measure

In ACME, we said the existing 100T press had an overall performance of 30% - but how did we calculate it?
Well, we know that for 50% of the time, the press is stopped?. and when it is running, it is only running at 70% of its design speed?. and during this time, it is also making 20% rejects.
The impact of these 3 elements combine as follows:
Availability (0.5) x Performance Rate (0.7) x Quality Rate (0.8) =