Exercise: [PROBABILITY I & II]

1. A number is chosen at random from the set {x : 1 x 50, x is an integer}. Find the probability of choosing a perfect square.

A C

B D

2. There are 12 apples in a basket of fruits. A fruit is taken at random from the basket. The probability

of getting an apple from the basket is . Calculate the total number of fruits in the basket.A 16 C 32B 20 D 64

3. There are 50 members in a Mathematic society and 30 of them are male. A further 30 female members join the club. If a number is chosen at random form the society, find the probability of choosing a female.

A C

B D

4. Table 1 shows the number of balls of red, blue and green in a box.

Colour Red Blue Green

Number 20 10 x

Table 1 If a ball is picked at random from the box, the

probability of getting a blue ball is . Find the value of x.A 5 C 15B 10 D 20

5. A box contains 10 yellow marbles, red marbles and some black marbles. When a marble is picked at random from the box, the probability of getting

a black marble is . Find the total number of marbles in the box.A 6 C 20B 10 D 26

6. There are 64 students in Class Science 5. The probability of picking a student who wears

spectacles at random is . Find the number of students who do not wear spectacles in the class.A 24 C 40

B 36 D 50

7. Table 3 shows the enrolment of a group of students in two streams.

Male Female

Science 22 20

Art 18 24

Table 3 A student is chosen of random from the group. What is the probability of choosing a female student from the Art stream?

A C

B D

8. A class consists of 26 girls and x boys. The probability of choosing a boy at random from the

class is . Find the value of x.A 14 C 18B 16 D 44

9. Diagram 3 shows six labelled cards in two boxes, P and Q,

Diagram 3 A card is picked at random from box P and then a card is picked at random from box Q. By listing the sample of all the possible outcomes of the event, find the probability that (a)a card with an odd number and the card labelled J are picked, (b)a card with a number which is multiple of 2 or the card labelled H are picked.

[5 marks]

10. In a quiz, there are three categories of questions consisting 6 questions on problem solving, 4 questions on critical thinking, and 5 questions on general knowledge. Each question is placed inside an envelope. All of the envelopes are similar and put inside a box. All the participants of the quiz are requested to pick two envelopes at random from the box.Find the probability that the first participant picks(a) the first envelope with a critical thinking question and the second envelope with a question on

general knowledge,(b) two envelopes with questions of the same category.

[5 marks]Answer: