Suppose a fair six-sided die is rolled once. If the value on the die is 1, 2 or 3 the die is rolled a second time. What is the probability that the sum total of values that turn up is at least 6?

Consider a finite sequence of random values $$X = \left\{ {{x_1},{x_2},{x_3}, - - - - - {x_n}} \right\}..$$ Let $${\mu _x}$$ be the mean and $${\sigma _x}$$ be the standard deviation of $$X.$$ Let another finite sequence $$Y$$ of equal length be derived from this $${y_i} = a.{x_i} + b,$$ where $$a$$ and $$b$$ are positive constants. Let $${\mu _y}$$ be the mean and $${\sigma _y}$$ be the standard deviation of this sequence. Which one of the following statements is incorrect?

A deck of 5 cards (each carrying a distinct number from 1 to 5) is shuffled thoroughly. Two cards are then removed one at a time from the deck. What is probability that the two cards are selected with the number on the first card is one higher than the number on the second card.

Consider a company that assembles computers. The probability of a faulty assembly of any computer is P. The company therefore subjects each computer to a testing process. This gives the correct result for any computer with a probability of q. What is the probability of a computer being declared faulty?