Question

we have 3 balls of color x and 4 balls of color y in an urn, what is the probability of drawing 2 balls of same color without replacement??

Answer 1

i have it forgotten :(

Answer 2

@jim_thompson5910

Answer 3

what is the probability that both balls are color x

Answer 4

C(2,3)/ C(2,7) ???

Answer 5

you have the notation mixed up

Answer 6

it should be C(3,2)/C(7,2)

Answer 7

what does that evaluate to

Answer 8

1/7

Answer 9

so the probability of picking 2 balls that are color x is 1/7

what is the probability of picking 2 balls that are color y?

Answer 10

Is there some trick.. isnt it just \(\frac{3}{7} \frac{2}{6} + \frac{4}{7}\frac{3}{6}\)

Answer 11

y: 2/7

Answer 12

so the probability of picking 2 balls that are color y is 2/7

add them up now

1/7+2/7 = 3/7

this means the probability of selecting 2 balls of the same color is 3/7

Answer 13

an easy way to do this is a tree diagram



so you can have

P(x + x) + P( y + y) = 3/7*2/6 + 4/7*3/6