If a discrete random variable X is defined as follows
$\mathrm{P}[\mathrm{X}=x]=\left\{\begin{array}{cl}\frac{\mathrm{k}(x+1)}{5^x}, & \text { if } x=0,1,2 \ldots \ldots . \\ 0, & \text { otherwise }\end{array}\right.$
then $\mathrm{k}=$
Numbers are selected at random, one at a time from two digit numbers $10,11,12 \ldots ., 99$ with replacement. An event $E$ occurs if and only if the product of the two digits of a selected number is 18 . If four numbers are selected, then probability that the event E occurs at least 3 times is
Two friends A and B apply for a job in the same company. The probabilities of A getting selected is $\frac{2}{5}$ and that of B is $\frac{4}{7}$. Then the probability, that one of them is selected, is
If a random variable X has the following probability distribution values
$\mathrm{X}$ | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
---|---|---|---|---|---|---|---|---|
$\mathrm{P(X):}$ | 0 | $\mathrm{k}$ | $\mathrm{2k}$ | $\mathrm{2k}$ | $\mathrm{3k}$ | $\mathrm{k^2}$ | $\mathrm{2k^2}$ | $\mathrm{7k^2+k}$ |
Then $P(X \geq 6)$ has the value