The probability that a washing machine will operate satisfactorily for 3 years is 0.82 while the probability that a floor polisher will operate satisfactorily over the same period of time is 0.78. Find the probability that in a 3-year period, only the floor polisher will operate satisfactorily.
I already got, P(A and B) = 0.78(0.82) = 0.6396
I'm not sure if I should subtract it with 0.78 or 0.82
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