00:01
For this question, we have the cumulative distribution function, fx, defined by x plus k, divided by 8.
00:14
And we have the support of this discrete random variable is 1, 2, 3.
00:24
Right so by the definition of cdf we know that fx should be equal to the probability that x is smaller than or equal to x right and then because this is a discrete random variable so this will be a discrete summation of the single probabilities right for all x that has values smaller than equal to this particular value.
01:06
So this, and we know that when x equals 3, we will have x, fx being 1, right? because we know that all the possible values of the random variable x will be smaller than or equal to 3.
01:25
Because we know this is a support.
01:29
And then we can see 3 plus k divided by 8 will be equal to 1.
01:37
So this means that k should be equal to 5.
01:42
So this is the answer for the first question.
01:45
And the second, write down f2 .6 for f2 .6.
01:58
And then we know that this is actually equal to probability that x is equal to 1 plus the probability that x is equal to 2.
02:18
And we know that we can calculate now f1 is actually equal to probability of x being 1.
02:32
And we know that f1 is equal to 1 plus 5 divided by 8, which will be equal to 3 over 4...