Question

a jar contains 4 green marbles, 5 red marbles, and 7 blue marbles. If two balls are selected randomly what is the probability of getting :
1. 1 green and 1 blue
2. 2 red
3. 1 blue and 1 red
4. 2 blue

Answer 1

hey help please?

Answer 2

well i just got confused.. give me a minute.

Answer 3

okay the title of lesson is combinations i got no idea how to do it lol

Answer 4

@ganeshie8

Answer 5

are you sampling with or without replacement?

Answer 6

without i think

Answer 7

then this is a hypergeometric distribution

Answer 8

a what????? lol explain

Answer 9

suppose you have a box with a red and b green balls. you grab k balls

the prob you get r red and g green balls (r+g=k) is given by

\[\frac{ _aC_r _bC_g}{_{(a+b)}C_k}\]

Answer 10

yeah i dont get it

Answer 11

\[\frac{_aC_r\cdot_b C_g}{_{a+b}C_k}\]

Answer 12

do you know what \[_nC_r\] is ?

Answer 13

not at all

Answer 14

\[{n\choose r}\]?

Answer 15

nope
i dont know any of this stuff

Answer 16

permutations/combinations?

Answer 17

i think it would be easier if we dont use combinations, zarkon..
it would be easier if if we do it like this..
for 1 green ball. 4/16..
1 blue ball after 1 green ball hass been selected.. 7/15. and then multiply them..
whats your view?

Answer 18

i knwo thats what this unit is called combinations

Answer 19

eh right. so it would be like 4/16*7/15 + 7/16*4/15.. right?

Answer 20

id think s if that was the case

Answer 21

wait but youd get the same thing right
7/60 + 7/60

Answer 22

yup.

Answer 23

then for the second part.. 5/16*4/15..
you get why?

Answer 24

which would equal 14/60 right because you dont change the denominator right or would it be 14/120

Answer 25

yeah.

Answer 26

so it is 14/120

Answer 27

am i right with the second part @RolyPoly ?

Answer 28

it should be 14/120..

Answer 29

no

Answer 30

14/60.. lol

Answer 31

the answer is 7/30

Answer 32

well
idk how to do this thn i am so lost im gonna fail lol

Answer 33

or 14/60 if you like

Answer 34

how

Answer 35

the solution is written above

Answer 36

okay so will you help by showing work on two three and four maybe if i see it on three ill be able to do it

Answer 37

P(blue first, then green)
= P(blue) x P(green after drawing a blue)
= 7/16 x 4/(16-1)
= a

P(green first, then blue)
= P(green) x P(blue after drawing a green)
= 4/16 x 7/(16-1)
= b

P(1 blue and 1 green)
=P(blue first, then green) + P(green first, then blue)
= a + b

Answer 38

now im deffinately confused i just ned a simple explanation

Answer 39

2 red, similar, despite the order of picking a red doesn't matter this time, since you don't the red ones are identical

Answer 40

what omg i need a tutor

Answer 41

Which part are you confused at?

Answer 42

2 BLUE

Answer 43

2 red actually all of it really

Answer 44

u gonna help k?

Answer 45

no thats not the question
@phi help please