I roll a fair die twice and obtain two numbers X1= result of the first roll and X2= result of the second roll. Given that I know X1+X2=7, what is the probability that X1=4 or X2=4?

By definition of conditional probability,

Assuming a standard 6-sided fair die,

Both outcomes are mutually exclusive with probability each, hence total probability .

Of the 36 possible outcomes, there are 6 ways to sum the integers 1-6 to get 7:

(1, 6), (2, 5), (3, 4), (4, 3), (5, 2), (6, 1)

and so a sum of 7 occurs of the time.

Then the probability we want is

4

step-by-step explanation:

u bout ugly as   a mf

step-by-step explanation: lol