EXPLANATION
Let name event A to the probability that the sensor A detect the monoxide and event B to the probability that the sensor B detects the monoxide.
We need to compute the probability that both sensors will detect it at same time:
[tex]P(A+B)=\lbrack P(A)-P(A\cap B)\rbrack+\lbrack P(B)-P(A\cap B)\rbrack+P(A\cap B)[/tex]Replacing terms:
[tex]P(A+B)=\lbrack0.98-0.93\rbrack+\lbrack0.94-0.93\rbrack+0.93[/tex][tex]P(A+B)=0.05+0.01+0.93=0.99[/tex]The probability that the present monoxide would be detected is 0.99 or 99%