Question

1. an urn contains 6 marbles of which 2 are blue, 2 are yellow and 2 are red. Sarah, Sally, and Sandra take their turn drawing two marbles each, one at a time, and without replacement.

a. if sarah is the first to draw two marbles, what is the probability she draws two blue marbles?

b. if sarah is the last to draw two marbles, what is the probability she draws two blue marbles.

c. if sandra is the last to draw two marbles, what is the probability she draws two marbles of the same color?

2. Patients undergoing joint revision surgery have a .30 probability of developing some sort of post operative infection. for those who develop an infection, the success rate or curing the infection is 94%.

a. construct a tree diagram for this situation

b. construct a table

c. if a person undergoes joint revision surgery, what is the probability the person will develop a post operative infection?

d. if a e person undergoes joint revision surgery, what is the probability the person successfully recovers from an infection?

3. suppose the next time you visit the grocery store, the amount of your purchase comes out to a whole dollar amount. what is the probability of such an occurrence?

4. The distribution of grades in the physical science department at a large university is given in the following table. grades are represented by numerical values according to the scale: A=4, B=3, C=2, D=1, and F=0

Grade 0 1 2 3 4

probability 0.10 0.12 0.35 0.30 ?

a. define an appropriate random value and list its range

b. what percent of the grades are A's?

c. what is the probability that a randomly chosen student taking a class in the physical science department will obtain a grade of C or better?

d. explain why the table represents a probability distribution

5. Let x=number of books purchased by students at your school during a given academic term. the probability distribution for X is given in the following table

X= number of books 1 2 3 4 5 6 7

Probability 0,.05 0.10 0.20 0.35 0.10 0.15 0.05

a. what values can x take? what does this set of values represent?

b. a student is randomly chosen from the student population. what is the probability that the student purchased five or more books during the current academic term?

c. what is the probability that a randomly chosen student purchased five or more books if it is known that the student purchased six books?

d. what is the probability that a randomly chosen student purchased six books if it is known that the student purchased five or more books?

Answer 1