Rolling two die

S

S_100

New member
Joined
Sep 27, 2019
Messages
27
Two identical dice are thrown, one after the other. What are the probabilities that (i) the total of the numbers shown is 6
I don't understand how the answer is 6/36 as opposed to 5/36

(1,5) (5,1)
(4,2) (2,4)
(3,3) ----> I don't understand why (3,3) is repeated twice, as rolling a three on die A and and rolling a three on die B are the same event - it can only occur once!
Whereas I understand rolling a 2 on die A and a 4 on die B are two different random variables to rolling a 4 on die A and a 2 on die B respectively.
 
Who says that the answer is 1/6 rather than 5/36?

The probability of 7 is 6/36 = 1/6.

The probability of 6 = 5/36 = the probability of 8.

The probability of 5 = 4/36 = 1/9 = the probability of 9.

The probability of 4 = 3/36 = 1/12 = the probability of 10.

The probability of 3 = 2/36 = 1/18 = the probability of 11.

The probability of 2 = 1/36 = the probability of 12.
 
If we expand the sum \(\displaystyle {(\sum\limits_{k = 1}^6 {{x^k}} )^2}\) SEE HERE
the coefficients tell us how many way there are to get each sum.
\(\displaystyle 4x^9\) tells us there are four ways to get a nine.
 
It rather simple to decide if you claim is true or not. Just list all 36 possible outcomes and count the number of times you see (3,3). If see (3,3) twice then you should count it twice, but before that please have your eyes examined.
 
S_100 said:
Two identical dice are thrown, one after the other. What are the probabilities that (i) the total of the numbers shown is 6
I don't understand how the answer is 6/36 as opposed to 5/36
Click to expand...
I think we're waiting to hear who said the answer is 6/36. Was this an error in the back of your textbook, or what someone else told you wrongly?

Yet another way to see that it is 5/36 is to note that the first die can be 1, 2, 3, 4, or 5, for each of which there is one choice for the second die; so the probability is 5/6 * 1/6 = 5/36.
 
You must log in or register to reply here.
Top