A flashlight has 10 batteries,out of which 4 | vedclass

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(A) Total number of batteries = $10$. Number of dead batteries = $4$. We need to select $3$ batteries without replacement. The probability that the fi

Vedclass · Accepted Answer

$ \frac{1}{30} $

Vedclass · Answer

(A) Total number of batteries = $10$. Number of dead batteries = $4$. We need to select $3$ batteries without replacement. The probability that the first battery is dead = $\frac{4}{10}$. After selecting one dead battery,the remaining number of batteries is $9$ and the remaining number of dead batteries is $3$. The probability that the second battery is dead = $\frac{3}{9}$. After selecting two dead batteries,the remaining number of batteries is $8$ and the remaining number of dead batteries is $2$. The probability that the third battery is dead = $\frac{2}{8}$. Therefore,the probability that all $3$ batteries are dead = $\frac{4}{10} 	imes \frac{3}{9} 	imes \frac{2}{8} = \frac{24}{720} = \frac{1}{30}$.

$A$ flashlight has $10$ batteries,out of which $4$ are dead. If $3$ batteries are selected without replacement and tested,then the probability that all $3$ are dead is:

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