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A bag contains $5$ black, $7$ red and $3$ white balls. If A ball is drawn from the bag at random. Then Find the probability that the ball drawn is:(iii) not black
A bag contains $5$ black, $7$ red and $3$ white balls. If A ball is drawn from the bag at random. Then Find the probability that the ball drawn is:(iii) not black
CBSE | Class 10 | Exercise 13.1 | Probability | RD Sharma
A bag contains $5$ black, $7$ red and $3$ white balls. If A ball is drawn from the bag at random. Then Find the probability that the ball drawn is:(iii) not black

(iii) Total number of black balls is $5$

We know that the Probability = Number of favourable outcomes/ Total number of outcomes

Therefore, the probability of drawing black ball P(E)$=5/15=1/3$

But, this is not what is required.

As we know that sum of probability of occurrence of an event and probability of non-occurrence of an event is $1$

$P(E)+P(\overset{\scriptscriptstyle\rightharpoonup}{E})=1$

$\frac{1}{3}+P(\overset{\scriptscriptstyle\rightharpoonup}{E})=1$

$P(\overset{\scriptscriptstyle\rightharpoonup}{E})=1-\frac{1}{3}$

$P(\overset{\scriptscriptstyle\rightharpoonup}{E})=\frac{2}{3}$

Hence, the probability of drawing a card that is not black is $2/3$

 

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