Posted by **Lucy** on Saturday, January 3, 2009 at 4:06pm.

a red number cube and a white number cube are rolled. Find the probability that the red number cube shows a 2, given that the sum showing on the two number cubes is less than or equal to 5.

My work: (red cube = [1,2,3,4]

white cube = [4,3,2,1]

Probability of a 2 on the red cube is 1/4. Is this correct?

- Pre-Cal -
**Damon**, Saturday, January 3, 2009 at 4:24pm
Block the whole matrix out with read along the top and white down

write all the sums in the boxes of the matrix, which contains 36 numbers.

Of those 36,

4+3+2+1 = 10

have sums less than or equal to 5

Of those 10, 3 show the number 2 on red

w1-r2 , w2-r2 , w3-r2

so 3/10

- Pre-Cal -
**bobpursley**, Saturday, January 3, 2009 at 4:24pm
If the sum is five, then red,white can be

1,4

2,3

3,2

4,1

if the sum is four, then

1,3

2,2

3,1

if the sum is three, then

1,2

2,1

if the sum is two, then

1,1

I see 10 possible combinations, and the red is 2 in 3 of them.

Pr(red=2, sum is =<5) is 3/10

- Pre-Cal -
**drwls**, Saturday, January 3, 2009 at 4:31pm
If the sum of the two cubes is 2, 3, 4, or 5 (all the possibilities that are allowed), then the red cube can only be 1, 2, 3 or 4.

The possibile combinations are:

W R

1 4

1 3

1 2

1 1

2 3

2 2

2 1

3 2

3 1

4 1

There are three combinations with a red 2 out of ten allowed. That makes the probability 3/10

- Pre-Cal -
**Damon**, Saturday, January 3, 2009 at 5:28pm
LOL - tomorrow we do Blackjack :)

## Answer This Question

## Related Questions

- stats - a hat contains a number od cubes: 15 red, 10 white, 5 blue and 20 black,...
- Pre-algebra - a red and blue number cube are rolled. determine the probability ...
- MATH - Two number cubes are rolledâ€”one red and one black. Explain why the events...
- math - Two number cubes are rolledâ€”one red and one black. Explain why the events...
- Math - Eduardo has a red 6-sided number cube and a blue 6-sided number cube. ...
- math - graysen has a green number cube and a white number cube. the faces of the...
- MATH PLEASE HELP - A single, standard number cube is tossed. What is the ...
- Advanced algebra - In which distributions does the variable, X, have a binomial ...
- Advanced algebra - In which distributions does the variable, X, have a binomial...
- algebra - In which distributions does the variable, X, have a binomial ...

More Related Questions