mathalgebra
posted by Anonymous .
7. A bag contains 5 red marbles, 6 green marbles, and 9 blue marbles. Suppose 3 marbles are chosen without replacement. What is the probability of choosing a red, a blue, and a red in that order?:
A. 9/320
B. 5/152
C. 1/1280
D. 1/38

Please only post your questions once. Repeating posts will not get a quicker response. In addition, it wastes our time looking over reposts that have already been answered in a another post. Thank you.

This answer was scored wrong, but I do not know why. If someone would kindly show me the error, I would appreciate it.
First choice probability: 5/20
Second choice probability: 6/19
Third choice probability: 9/18
Total Probability: (5/20)(5/19(9/18)=3/76
This answer is not featured above but the math seems correct. Each successive choice has fewer balls remaining, and the correct number of the desired balls for the next choice still remains in the bag for all the choices. The total probability is the product of the probability of each choice. 
(¡) 5/17

the answer is B. when you multiply you get (225/6840) simplifing this and you will get 5/152.

A cup contains 9 red jelly beans, 8 green jelly beans, and 8 blue jelly beans.
If a jelly bean is randomly chosen, what is the probability that it is not green? Write your answer as a simplified fraction. 
17/25

the answer Red then blue the red is D.
1 of 38 or 2.63% chance
5 red chances /20 balls *
9 blue /19 * 4 red balls left /18
= .25 X .47368 * .2222 = .0263
or 1/38 
A bucket contains 5 yellow and 7 red balls. If 2 balls are selected randomly without replacement, what is the probability that they will both be yellow?

5/20*9/19*4/18 = 1/4*9/19*2/9 =
1/2*1/19 = 1/38