Three coins are tossed simultaneously. What are the odds :

(a) in favour (b) against of getting all three heads?

Twenty tickets are numbered 1 to 20. One ticket is drawn at random. What are the odds:

(a) in favour (b) against getting a prime number on the ticket ?

Six books, 3 of which are on chemistry, are arranged on a shelf. Find the probability that:

(i) the books on chemistry are together.

(ii) not all three books on chemistry are together.

Five digit numbers are formed by using digits 2, 3, 4, 5 and 6. Find the probability that the number formed will be :

(i) even           (ii) odd          (iii) greater than 50000.

518.

A pinochle deck of card consists of 2 aces, 2 kings, 2 queens, 2 jacks. 2 tens and 2 nines of each of the four suits and there are no other cards of lower values. One card is drawn at random from the pack. What is the probability that the card is:
(a) a king?                                            (b) not a king?

A die is rolled twice. What is the probability that:

(a) the number appearing on the first toss is greater than that on the second toss?

(b) the product of the numbers appearing is ≥ 24?