2013 Mock QB7

[PJD]

Hi all, 
Appreciate any feedback on this.

[Peter]

Hi all, 
Appreciate any feedback on this.

You have spotted at the end of part C that you have a number that appears to be very high.

I suggest that you look into how failure rates of parallel systems should be combined. You have added the failure rates (which would imply that the failure rate for the more resilient 2oo3 systems is double a single system which is clearly nonsense) whereas to affect the function of the overall system, BOTH of the subsystem elements must be failed at the same time, so the frequencies should be multiplied (and hence give a failure rate less than any single system).

I think you have missed the point of part c. Aside from the addition vs multiplication error, think about why the question tells you the response time of the voting system and then try to work out what you should have been calculating.

Peter

[PJD]

Many thanks.
Ok, will do.