# Thread: omg probability is so hard!! =[[

1. ## omg probability is so hard!! =[[

can u show me how to do this step by step?

Jerry has a CD case that contains 4 country music CDs, 1 rock-and-roll CD, 2 rap CDs, and 3 Tejano CDs. What is the probability of Jerry randomly selecting a Tejano CD and then, without replacing it, randomly selecting a rap CD from his case? A

B

C

D

2. Originally Posted by whatxxever_2009
can u show me how to do this step by step?

Jerry has a CD case that contains 4 country music CDs, 1 rock-and-roll CD, 2 rap CDs, and 3 Tejano CDs. What is the probability of Jerry randomly selecting a Tejano CD and then, without replacing it, randomly selecting a rap CD from his case? A

B

C

D
The probability of drawing a Tejano CD is as follows:

There are 3 Tejano CDs, but we have 4+1+2+3=10 CDs total. So the probability of him picking a Tejano CD first would be $\displaystyle \frac{3}{10}$. If he then picks a Rap CD without replacement, then the total number of possible CDs drops down to 9. Thus, the probability of him drawing a Rap CD after he draws a Tejano CD is $\displaystyle \frac{3}{10}\cdot\frac{2}{9}=\boxed{\frac{1}{15}}$

Does this make a little more sense now? If you're still lost, please post back.

Note that I moved your thread from the Geometry forum to the Probability and Stats forum.

3. oh ok. but why do u have to multiply them together? whenever i have a problem like this will i always have to multiply them?