Question

Help, please..

Answer 1

Please post questions,

Answer 2

@UnkleRhaukus @experimentX @Hero help needed...i will be bck later just post the solution and the explanantion...thnks

Answer 3

There are a total of 12 discs. 8 of which are blue and 4 are red.

At the first attempt, one disc is taken out and not replaced. so by the second time another disk is taken out there are a total of 11 disks now. ...

The diagrams show the possible outcomes.

When taking out the first disc. the probability that a blue one will come out is 8 out of 12 which is why there is a 2/3. and there are 4 red out of the12 which is why the 1/3 comes out when simplified.

Lets assume that a blue disc was taken out. which is the top triangle on right. now there are only 11 discs. 7 are blue and 4 are red. so the probability of taking out a blue is 7/11 while taking a red one out is 4/11. (they mixed up numbers in the image).

Now though lets assume that instead of a blue disc a red one was taken out. now there are 3 red discs out of the 11 left and there are 8 blue discs. The new probability of taking out a red is 3/11 while that of blue is 8/11.

A)the probability that both discs are red :
on the first try the probability that we take out a red one we said that it was 1/3
on the second try the probability we take out a red one again we said was 3/11.

to find out part a we multiply these across

1/3 X 3/11= 3/33 = 1/11

B) at least one out of the two discs is blue:
probability on first attempt 2/3
probability on second 7/11

we multiply across:

2/3 X 7/11= 14/33 this can't be simplified anymore so your answer is

14/33

Answer 4

By the way, on (b) it said at least one blue so both blue could be chosen. its the same answer.

For (iii) A third disc is taken out, probability that all are red:

we know that the probability for both to be red is 1/11 from previous now we need to find out the probability for the third pick

from the previous instructions we were told that two discs were taken out and none of those two were replaced. So there is now a total of 10 discs instead of the 12.

since we took out 2 red discs already, there are only 2 left out of the 4.

the probability thus is 2/10= 1/5

we multiply it by 1/11
and get

1/55.

Answer 5

the b part is wrong i guess, the 14/33?

Answer 6

I think I see what I over looked. Sorry, This is my new explanation for b

Since we only have to take out atleast 1 blue disk, we don't have to worry about the probability the second time. I don't know if you understand me?

the answer would be just 8/12 or 2/3

Answer 7

bro, i understnd u, thepart which was wrong is...ii) b) B) "at least one out of the two discs is blue"

Answer 8

is it 2/3? or not that either?

Answer 9

nope...its 10/11