0.05 due to equipment failure and op error
0.4 due to op error.
Therefore 0.35 are due to op error alone (the 0.4 includes the 0.05 which
are due to both causes).
So for a) you need 0.1+0.35+0.1
for b) we have 0.35
for c) we have 1 minus the answer to a).