Question

In a box there are 10 non-defective and some defective bulbs. If the probability that a bulb selected at random from the box to be defective is 27/27 then find the number of defective bulbs.

Answer 1

Answer:

The number of defective bulbs is 12

Step-by-step explanation:

Solution:-

In a box there are 20 non-defective and some defective bulbs

The probability that a bulb selected at random from the box found to be defective is 3 /8

probability = number of defective bulbs / total number of possible outcomes

From given,

Let the number of defective bulbs be "x"

Let the number of defective bulbs be "x"total number of possible outcomes = 20 + x

Therefore,

$\frac{3}{8} = \frac{x}{20 + x}$

$60 + 3x = 8x$

$5x = 60$

$x = 12$

Thus number of defective bulbs is 12.

Answer 2

Answer:

4

Step-by-step explanation:

Given:- 10 non-defective bulbs. Probability of the selected bulb being defective = 2/7.

To Find:- Number of defective bulbs.

Solution:-

Let the number of defective bulbs be x.

Number of non-defective bulbs = 10.

∴ Total number of bulbs = x + 10

Probability(a bulb being defective) = $\frac{x}{x + 10}$

According to the question,

                ⇒ $\frac{x}{x + 10} = \frac{2}{7}$

                ⇒ $7x = 2x + 20$

                ⇒ $7x - 2x = 20$

                ⇒ $5x = 20$

                 ⇒ $x = 4$

Therefore, number of defective bulbs is 4.

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