# bulb probability

• Jan 13th 2010, 02:47 AM
thereddevils
bulb probability
Two percent of the bulbs produced by a factory are not usable .Find the smallest number of bulbs that must be examined so that the probabiltiy of obtaining at least one non-usable bulb exceeds 0.5 .
• Jan 13th 2010, 02:58 AM
mr fantastic
Quote:

Originally Posted by thereddevils
Two percent of the bulbs produced by a factory are not usable .Find the smallest number of bulbs that must be examined so that the probabiltiy of obtaining at least one non-usable bulb exceeds 0.5 .

X ~ Binomial(n = ?, p = 0.02).

Solve $\Pr(X \geq 1) > 0.5 \Rightarrow \Pr(X = 0) < 0.5$ for the smallest integer value of n.