# Probability

posted by
**Mary**
.

Find the conditional probability. Suppose one card is selected at random from an ordinary deck of 52 playing cards.

Let A = event a queen is selected

B = event a diamond is selected

Determine P(B[A)

How do you go about solving this one?

I know there are 4 queens, 13 diamonds

13/52 4/52 = 17/52

Is that correct?

One last question...

The age distribution of students at a community college is given below.

Age(years) # Numbers of students

Under 21 - 411 students

21- 25 - 407 students

26-30 - 201 students

31-35 - 51 students

Over 35 - 26 students

A student from the community college is selected at random. Find the conditional probability that the student is between 26- 30 given that he or she is at least 26.

I would also like to know how to work this problem out.

Please help.

If a queen is selected, there are 51 cards left, and 4 diamonds. So Pr(B given A) is 4/51.

If she is at least 26, then there are a total of 201+51+ 26 students in that age pool. Pr of being in 26-30 age group then is 201/total above

Probabality is always the number of likely draws out of the total possible pool.