Question

find the probability that one dice of a pair of dice shows 4 if the sum of the two is greater than or equal to 9

Answer 1

i calculated the probability to be 22/36 or 11/18

Answer 2

i get 1/9 * 36/10 = 2/5

Answer 3

how did u get 1/9 and 36/10

Answer 4

i know the only two possible choices were 4 and 5 to make the sum equal 9 or 10

Answer 5

i meant 5 and 6

Answer 6

conditional probability:
P(you have 4 AND sum >=9) = 4/36
P(sum >=9) = 10/36

Answer 7

10/36?

Answer 8

4 ways of making 9
3 ways of making 10
2 ways of making 11
1 way of making 12

Answer 9

ok. i get it now! how did u get 36? 6.6 because a dice has 6 faces

Answer 10

right , 6*6 = 36 possible combinations of rolling 2 dice

Answer 11

i don't understand the question itself. it says that one dice should show 4

Answer 12

so if one dice has to show 4 the possibility=1/6 for that dice. and not 4 is 5/6

Answer 13

then for the other dice is has to either be 5 or 6. because 4+5=9 and 4+6=10

Answer 14

u can't add anything to 4 to make it 11 or 12 with the other dice because a dice has 1-6

Answer 15

given sum>= 9, there are 10 possible ways the dice can be arranged right?
then of those 10 only four have a 4 showing.
4,5
5,4
4,6
6,4

Answer 16

yes

Answer 17

ok i got it now! ways that the combination of both number is greater than or equal to 9 is 10.

Answer 18

not including the fact that one has to be 4

Answer 19

hence, the combination of numbers than can make the sum >= 9 is 10/36 whereas when one dice has 4 and the sum is >= is only 4 ways

Answer 20

thanks for clearing it up for me :)

Answer 21

no problem

Answer 22

one last question

Answer 23

@dumbcow you had 4/36*36/10? why did u invert it? did u divide both probabilities?

Answer 24

comes from formula when using conditional probability
\[P(A|B) = \frac{P(A and B)}{P(B)}\]

Answer 25

A -> one dice is 4
B -> sum >= 9

Answer 26

oh ok! i forgot about that formula -_- thank you!

Answer 27

thank u :)