Hi 2e2,

Some of you have requested for extra questions on Probability.
Try them out!

1) A pouch contains 60 marbles - 34 are red, 21 are white and the remaining are blue. A marble is picked at random from the pouch.
What is the probability of picking a
(a) blue marble?
(b) red or blue marble?

Ans: (a) 1/12 (b) 13/20

2)A bag contained nine cards 1 to 9. One ball is drawn at random from the bag.
(a) List the elements of the sample space S.
(b) E is the event of drawing a multiple of 4. List the outcomes of E and state n(E).
(c) Find the probability of drawing a card which is a multiple of 4.
(d) Find the probabilty of drawing a card which is a prime number.

Ans: (a) S={1,2,3,4,5,6,7,8,9} (b) E={4,8} ; n(E)=2 (c) 2/9 (d) 4/9

3) A letter is chosen at random from the word "DIFFICULT". What is the probability that the letter chosen is a
(a) 'F'?
(b) a vowel?
(c) a consanant?
(c) a 'I' or a 'T'?

Ans: (a) 2/9 (b) 1/3 (c) 2/3 (d) 1/3

4) There are 26 white beads, 10 red beads and 4 orange beads in the box. One bead is chosen at random, find the probability that the bead chosen is an orange bead.

Ans: 1/10

5) There are 20 sticks in a container. 8 are green, 5 are red, 6 are black and the remaining are grey. John chose one stick at random. He picked a red one. After putting it aside, he chose one more stick at random. What is the probability that the stick chosen is a red one again?

Ans: 4/19