Question

Someone help I will give medal

Question involving the rolling of two fair dice.
What is the probability of one of the dice showing 3 or the sum being at least 8?

Answer 1

Well do you know how to compute probability?

Answer 2

yes I do, I thought the answer was 16/36 but it was wrong

Answer 3

So the probability of rolling 3 is equal on /both/ of them so we just leave that probability as 1/6th, not 1/12th. Does that help?

Answer 4

Huh? On a fair dice there's a 1 in six chance of rolling a 3.

Answer 5

yes but can't you roll a 3 on lets say die 1 or die 2?

Answer 6

Yes, but that's 2/12 chance, which simplifies down to 1/6.

Answer 7

oh

Answer 8

Actually, 16/36 can be simplified. Maybe the answer needs to be simplified. What format is the test?

Answer 9

it simplifies it for you

Answer 10

Oh. well then.

Answer 11

So we've got 1/6th. Then we need to work out the chance of rolling a sum of of over eight and add it to 1/6th.

Answer 12

would it be over 36?

Answer 13

The denominator?

Answer 14

yes

Answer 15

IDK XD
I'll work it out.

Answer 16

So how many combinations are there that equal above 8?

Answer 17

5

Answer 18

So there is a 5/36 (yeah, it is 36) chance of getting +8. So find a common denominator between 1/6th and 5/36ths and add them together.

Answer 19

i made a mistake

Answer 20

its the sum of at least 8

Answer 21

which equals 15/36

Answer 22

Ok. So still, multiply 'till you've got a common denominator + add them together.

Answer 23

quick question

Answer 24

Yeah?

Answer 25

wouldn't the probability of getting a 3 on one die be 10/36

Answer 26

I think the probability of 1 showing a 3 is 11/36.
http://www.sms.rcs.k12.tn.us/TEACHERS/flaniganj/TEST/chapter_9_files/i0100000.jpg

Answer 27

Well 36/6 = 6 so it's 6/36

Answer 28

where is the 6 coming from?

Answer 29

would the answer be 25/36

Answer 30

You can get a 3 six different way on the first die, and 6 different ways on the second die. But two of those is (3, 3) so you subtract 1 to get 11/36 ways.

11/36 + 15/13 = 26/36

Answer 31

* 11/36 + 15/36 = 26/36

Answer 32

oh i see

Answer 33

the answer is still wrong

Answer 34

Well you're multiplying both sides of the fraction to give it 36 as a denominator, and you need to times 6 by 6 to get to 36, so so you also multiply 1 by six to get from 1/6 to 6/36, which you can add to 15/36.

Answer 35

Which by my admittedly thirteen-year-old brain is 21/36.

Answer 36

did you try the 25/36 you came up with?
I'm guessing they want you to exclude the double roll.

Answer 37

yeah probably because it says one 3 not 2

Answer 38

was that it?

Answer 39

i didn't try it yet. I only have 2 attempts left

Answer 40

do you think 25/36 would be the right answer if its not including the double roll

Answer 41

yeah, not including it, it's 25/36.
including it, it's 26/36 or 13/18.

Answer 42

no its not it either

Answer 43

;(

Answer 44

red = one 3
blue = sum at least 8