$A$ and $B$ toss a coin alternatively, the first to show a head being the winner. If $A$ starts the game, the chance of his winning is
$5/8$
$1/2$
$1/3$
$2/3$
If two balanced dice are tossed once, the probability of the event, that the sum of the integers coming on the upper sides of the two dice is $9$, is
A single letter is selected at random from the word “$PROBABILITY$”. The probability that the selected letter is a vowel is
If in a lottary there are $5$ prizes and $20$ blanks, then the probability of getting a prize is
A coin is tossed. If the out come is a head, a die is thrown. If the die shows up an even number, the die is thrown again. What is the sample space for the experiment?
In a single throw of two dice, the probability of getting more than $7$ is