Question

Out of 400 bulbs in a box, 15 bulbs are defective. One bulb is taken out at random from the box. Find the probability that the drawn bulb is not defective.

Answer 1

Given: Out of 400 bulbs, 15 are defective; one bulb is drawn at random.

Step-wise calculation:

1. Number of non‑defective bulbs

= 400 – 15

= 385

2. Probability (not defective) = `"Favourable"/"Total"`

= `385/400`

3. Simplify: `385/400`

= `77/80`

= 0.9625

= 96.25%.

The probability that the drawn bulb is not defective is `77/80` (≈ 0.9625 or 96.25%).