# Sampling without replacement - Probability of obtaining 3 defectives.

• November 10th 2011, 08:45 AM
mathproblems
Sampling without replacement - Probability of obtaining 3 defectives.
Six microprocessors are randomly selected from a lot of 100 microprocessors among which 10 are defective. Find the probability of obtaining at least three defective microprocessors.

((90,6)*(10,3))/(100,6)

Is(Nerd) this correct? Thank you.
• November 10th 2011, 09:07 AM
Plato
Re: Probability
Quote:

Originally Posted by mathproblems

Six microprocessors are randomly selected from a lot of 100 microprocessors among which 10 are defective. Find the probability of obtaining at least three defective microprocessors.

((90,6)*(10,3))/(100,6)

Is(Nerd) this correct? Thank you.

NO

Try $\sum\limits_{k = 3}^6 {\frac{{\binom{90}{6-k}\binom{10}{k}}}{\binom{100}{6}}}$