we are given that total number of Tvs is 9 and the defective tvs out of 9 is 2 thus we have 7 Tvs working normally. Remember that after first selection there is no replacament.
probability of both TVs working is given by 7/9*6/8= 7/12 = 0.5833
The probability of at least one TV working is given by total probability - probability of both TVs working
probability of at least one not working = 1-7/12 = 5/12 = 0.4167
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