Descriptive Statistics and Probability Two Marks Questions

11th Standard

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Time : 00:45:00 Hrs
Total Marks : 20
10 x 2 = 20
1. Find the first quartile and third quartile for the given observations
2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22

2. An aeroplane flies, along the four sides of a square at speeds of 100,200,300 and 400 kilometres per hour respectively. What is the average speed of the plane in its flight around the square.

3. A die is thrown twice and the sum of the number appearing is observed to be 6. What is the conditional probability that the number 4 has appeared at least once?

4. Suppose one person is selected at random from a group of 100 persons are given in the following

 Psychologist Socialist Democrate Total Men 15 25 10 50 Women 20 15 15 50 Total 35 40 25 100

What is the probability that the man selected is a Psychologist?

5. A die is thrown. Find the probability of getting
(i) a prime number
(ii) a number greater than or equal to 3

6. There are 1000 students in a school out of which 450 are girls. It is known that out of 450, 20% of the girls studying in class XI. A student is randomly selected from 1000 students. What is the probability that the selected student is from class XI given that the selected student is a girl?

7. From a pack of 52 cards, two cards are drawn at random. Find the probability that one is a king and the other is a queen.

8. An unbiased die is thrown. If A is the event ‘the number appearing is a multiple of 3’ and B be the event ‘the number appearing is even’ number then find whether A and B are independent?

9. Let P(A)=$\frac{3}{5}$ and P(B)=$\frac{1}{5}$ . Find P(A∩B) if A and B are independent events.

10. An investor buys Rs. 1,500 worth of shares in a company each month. During the first four months he bought the shares at a price of Rs. 10, 15, 20 and 30 per share. What is the average price paid for the shares bought during these four months? Verify your result.