Gah i posted 2 questions about my test earlier, cud u pls check it

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- Apr 22nd 2008, 11:36 PMandrew2322Probability Test
Gah i posted 2 questions about my test earlier, cud u pls check it

- Apr 23rd 2008, 12:44 AMMoo
Hello,

Questions 1, 2 and 3 are ok.

Question 4 :

Quote:

a.) The first marble picked is black and the second is red: 5/36

Quote:

b.) Obtaining 2 white marbles: 1/16

- Apr 23rd 2008, 12:48 AMandrew2322sorry
Find One Lol

- Apr 23rd 2008, 12:52 AMMoo
Good job ! (Clapping)

- Apr 23rd 2008, 01:01 AMandrew2322hey
booo

- Apr 23rd 2008, 01:03 AMMoo
Yes ^^

Unless I made mistakes too, but all the reasoning is correct ! - Apr 23rd 2008, 01:05 AMandrew2322hey
haha i doubt two people can make the exact same mistake

- Apr 23rd 2008, 04:55 AMcolby2152
So far #1 and #2 are correct, but #3 has an error...

Quote:

3.) A red and a black die labelled 1 - 6 are thrown simultaneously, find the probability of:

a.) A number less than 5 on the red die: 2/3

b.) A number less than 5 on the red die but a totla of 10 altogether: 1/36

c.) Both die adding to 10: 1/12

given that, b) should be equal to $\displaystyle \frac{2}{3}*\frac{1}{6} = \frac{1}{9}$

c) is correct, three possibilities out of thirty-six

Quote:

4.) There is 3 white marbles, 4 blue marbles and 5 red marbles in a bag. Find the probabilty of if marbles are picked WITH REPLACEMENT:

a.) The first marble picked is black and the second is red: 5/36

b.) Obtaining 2 white marbles: 1/16

b) $\displaystyle \frac{3}{12}^2 = \frac{9}{144}$, Remember, the white marble is replaced by another white marble.

#5, #6 and #7 are all correct

Note: Best way to solve #7 is by using a Venn diagram - Apr 23rd 2008, 09:09 AMMoo
He said it was blue

Quote:

b) $\displaystyle \frac{3}{12}^2 = \frac{9}{144}$, Remember, the white marble is replaced by another white marble.

Since there is replacement, the probability to get 2 marbles will be the product of the probabilities of getting 1 marble, that is to say 1/4²=1/16, isn't it ?

Actually, 9/144 is 1/16... :p - Apr 23rd 2008, 09:11 AMMoo
- Apr 25th 2008, 12:01 PMcolby2152