Question 177904
Battery quality is an independent event, probabilities multiply.
Probability of 1 defect free battery = 1-0.08=0.92
Probability of 2 defect free batteries= 0.92*0.92=0.846.
Probability of 3 defect free batteries= 0.92*0.92*0.92=0.779.
Probability of 4 defect free batteries= 0.92*0.92*0.92*0.92=0.716.
The probability is 71.6% that you'll have 4 defect free batteries.