Assume that the box contains 11 balls: 4 red, 4 blue, and 3 yellow. As in the text, you draw one ball, note its color, and if it is yellow replace it. If it is not yellow you do not replace it. You then draw a second ball and note its color.
(1) What is the probability that the second ball drawn is yellow?

(2) What is the probability that the second ball drawn is red?

Question

Assume that the box contains 11 balls: 4 red, 4 blue, and 3 yellow. As in the text, you draw one ball, note its color, and if it is yellow replace it. If it is not yellow you do not replace it. You then draw a second ball and note its color.
(1) What is the probability that the second ball drawn is yellow?  

(2) What is the probability that the second ball drawn is red?

anonymous · Answer

(1) if the first ball was yellow then the answer is 2/9
if the first ball wasnt yellow then the answer is 2/8

(2)if the first ball was yellow then the answer is 5/9
if the first ball wasnt yellow then the answer is 1/8 OR 2/8 (because the first ball can be red OR blue) ;) hope this helps!

cwrw238 · Answer

if it is replaced then P(2nd = yellow) = 3/11
  not replaced      ..    ..              ..     =  3/10

anonymous · Answer

im confused what is the answer for part one

anonymous · Answer

2/9

anonymous · Answer

thats not right

anonymous · Answer

its not?

cwrw238 · Answer

i'm confused also how did u get 2/9  kelly?

anonymous · Answer

nope my homework thing tells you if its wrong

anonymous · Answer

homework thing? is it multiple choice?

cwrw238 · Answer

i think its 3/10 + 3/11 =  63/110

anonymous · Answer

no it just tells you if its right or wrong

anonymous · Answer

how?

anonymous · Answer

63/110 isn't right

anonymous · Answer

thats not wat i wrote..?

cwrw238 · Answer

hhmm - must admit probability not my strong point

anonymous · Answer

yah.. i guess its not really mine either..;)

anonymous · Answer

ok, well, it looked right... we can try to pick it apart if you're sure it's not right.

cwrw238 · Answer

oh - didn't include probabilities oif first draw

anonymous · Answer

Prob of yellow on 2nd ball:

P of yellow on first ball = 3/11, then replace, then 3/11 on 2nd ball
and
P of not yellow on first ball = 8/11, then no replace, then yellow 3/10 on 2nd ball

anonymous · Answer

(properly, that middle "and" should be an "or")

anonymous · Answer

(3/11)(3/11)   +   (8/11)(3/10)

= 9 /121   + 24/110

Maybe?  I'm thinking and typing... this isn't my best topic either...

cwrw238 · Answer

yellow first  and second
= 3/11 * 3/11
yellow not first then yellow  
= 8/11 *  3/10

9/121 + 24/110

anonymous · Answer

love it :)

cwrw238 · Answer

jake - yes thats the way

cwrw238 · Answer

= 0.29 as a decimal   correct to 2 places

cwrw238 · Answer

or as a fraction 177/605