If standard deviation of a random variable X is 3 and Y = -5X -10 then SD(Y) = -85.

A hand of three cards is chosen from a standard deck of 52 cards. You get Rs 3 for each heart in your hand. If X denotes the random variable measuring your gain, then find expected value of X.

In a trial, the null hypothesis is that an individual is innocent of a certain crime. Would the legal system prefer to commit a type-1 or type-II error with this hypothesis?

What is the probability that a person arriving at the booth will have to wait?

If the arrival rate is 12 per hour and service rate is 4 per hour, then the probability of no customer in queue is 0.3.

A drunk has five keys on his key chain, and only one will open the front door of his house. He tries each key until he finds the right one. Assume that he is so drunk that he may repeat the wrong key any number of times. On average how many trials he will make to open the front lock of his house.

If a researcher wants to half the standard error of the estimator of the mean then he/she will increase the sample size 4 times.