You have a 4-card deck containing a queen, a jack, a 10, and a 9. You draw a random card, then put it back and draw a second random card. Use a tree diagram to calculate the probability that you draw exactly 1 queen.

Question

anonymous · Answer

i think its 1/4 but im not sure

mathmate · Answer

The proper way:
draw the tree diagram and count how many outcomes have exactly 1 queen.
To calculate then you know that you need
QX, or
XQ
To get a Q in each of the two steps, the probability is 1/4.
To get an X (not queen) in each of the two steps, the probability is 3/4.
P(QX)=(1/4)(3/4)=3/16
P(XQ)=(3/4)(1/4)=3/16
So what is the probability of getting exactly 1 queen?

anonymous · Answer

1/4?

mathmate · Answer

Not exactly.
Have you done the addition and multiplication rules in probabilities?

anonymous · Answer

no im in independent studies so i teach mysef pretty much

mathmate · Answer

You may want to review the topic because many problems involve applying these two rules in different situations. Since the application can be on a wide variety of areas in many different ways, a thorough understand is required. See if your text book has anything on it. If not, there are many articles on the Internet, such as: http://www.stat.berkeley.edu/~bradluen/stat2/lecture16.pdf

anonymous · Answer

can you just give me the answer please?

amistre64 · Answer

we dont just give out answers ... thats really no way for you to teach yourself

anonymous · Answer

i got it now 3/8?

mathmate · Answer

This is correct.

mathmate · Answer

But I hope it was not a guess.