Question

A bag has 4 green marbles, 3 red marbles, and 3 yellow marbles. What is the probability that you pick a red marble, do not replace it, and pick another yellow marble?
A. 2/15
B. 1/15
C. 1/9
D. 1/10

Answer 1

Do you know how to draw a tree diagram of probabilities?

Answer 2

Yes

Answer 3

What do you think the answer is?

Answer 4

C?

Answer 5

Okay - hang on, im working on it

Answer 6

Alright

Answer 7

Okay - it definitely cannot be c... I've got the answer but I'll take you through the correct process:

1) Tell me: What is the probability of picking up a RED marble?

Answer 8

3 out of 10

Answer 9

YES! well done.

Now,

2) Since you have removed one marble, tell me: How many marbles in total now?!?!

Answer 10

7?

Answer 11

Nope - try again - if I have 10 alltogether to start with and i remove one.........


(hINT : 10 - 1!!)

Answer 12

Oh i thought you meant one color. 9

Answer 13

okay, sorry!

So tell me what is the probability of getting a yellow:
To figure this out we know that

1) The total has been reduced to 9 and
2) There are still 3 yellow marbles

So .....the probability of getting a yellow is???????

Answer 14

1/3 !

Answer 15

3/9

Answer 16

YES! as 3/9 = 1/3

Answer 17

So, we know that

Pr (RED) = 3/10
Pr (YELLOW) = 3/9

.............are you with me?

Answer 18

Yes

Answer 19

Now, what I am about to tell you is IMPORTANT (REMEMBER THIS!!!)

** If you are picking marbles CONSECUTIVELY (ONE AFTER THE OTHER)
=> red AND yellow
YOU MUST *****MULTIPLY**** THE PROBABILITIES TOGETHER!!!
Do you promise you will remember this!?!?

Calculate this now and see what you get... :)

Answer 20

1/10?

Answer 21

Very Good Mr. Nuggets!

Answer 22

CORRECT! Do you understand the process now?

Answer 23

Lol! Yes i understand it now. And thank you for the help.

Answer 24

Your welcome :)

Answer 25

nice work @BarbaraKara

Answer 26

Why thankyou! @pengembara_bumi1