Recent questions tagged expectation

6 votes
2 answers
35
Two balls are drawn uniformly at random without replacement from a set of five balls numbered $1,2,3,4,5.$ What is the expected value of the larger number on the balls dr...
1 votes
1 answer
37
2 votes
1 answer
39
Let the random variable X represent the number of times a fair coin needs to be tossed till two consecutive heads appear for the first time. The expectation of X is _____...
1 votes
0 answers
40
Let X and Y are two random variables with E(X)=10,E(Y)=20 and Var(X)=25,Var(Y)=36 and E(X.Y)=225.Now consider Z=aX-bY+1.Find a and b when E(Z)=1 and Var(Z)=1.
2 votes
2 answers
42
Suppose $X$ and $Y$ are two independent random variables both following Poisson distribution with parameter $\lambda$. What is the value of $E(X-Y)^2$ ?$\lambda$$2 \lambd...
0 votes
1 answer
43
A simple graph with n vertices is constructed by randomly and independently placing an edge between every two vertices with probability p. What is the expected no. of nod...
1 votes
0 answers
46
A man with n keys wants to open a lock. He tries his keys at random.The expected number of attempts for his success is (keys are replaced after every attempt)a) n/2b) nc)...
47 votes
4 answers
47
If a random variable $X$ has a Poisson distribution with mean $5$, then the expectation $E\left [ \left ( x+2 \right )^{2} \right ]$ equals ___.
1 votes
1 answer
52
A coin is flipped n times. Assuming that the flips are independent, with each onecoming up heads with probability p, what is the probability that there is a string of kco...
2 votes
1 answer
54
Let there be a string of 10 bits generated uniformly at random (each bit could be 0 or 1 with equal probability). What is the expected number of appearances of a substrin...
3 votes
0 answers
55