SAT Math 2 HELP!

Test Preparation SAT Subject Test Preparation
1

<p>Here's the question from Dr. Chung's:</p>

<p>If the probability that a light bulb is defective is 1/10, what is the probability
that a package of 10 light bulbs has exactly two defective bulbs? </p>

<p>a. 0.01 b. 0.10 c. 0.19 d. 0.25 e. 0.33</p>

<p>The answer is (C). Can anyone explain why?</p>

<p>Thanks</p>

2

<p>This is a fairly straightforward binomial distribution problem. The probability of exactly 2 defective bulbs is</p>

<p>(10C2)*(1/10)^2 * (9/10)^8</p>

<p>Which is roughly .194.</p>