#### Descriptive Statistics and Probability Model Question Paper

11th Standard

Reg.No. :
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Time : 01:00:00 Hrs
Total Marks : 50
5 x 1 = 5
1. Which of the following is positional measure?

(a)

Range

(b)

Mode

(c)

Mean deviation

(d)

Percentiles

2. When calculating the average growth of economy, the correct mean to use is?

(a)

Weighted mean

(b)

Arithmetic mean

(c)

Geometric mean

(d)

Harmonic mean

3. Harmonic mean is the reciprocal of

(a)

Median of the values.

(b)

Geometric mean of the values.

(c)

Arithmetic mean of the reciprocal of the values.

(d)

Quartiles of the values.

4. Median is same as

(a)

Q1

(b)

Q2

(c)

Q3

(d)

D2

5. Harmonic mean is better than other means if the data are for

(a)

Speed or rates.

(b)

Heights or lengths.

(c)

Binary values like 0 and 1.

(d)

Ratios or proportions.

6. 5 x 2 = 10
7. A family has two children. What is the probability that both the children are girls given that at least one of them is a girl?

8. 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?

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

10. 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.

11. Data on readership of a magazine indicates that the proportion of male readers over 30 years old is 0.30 and the proportion of male reader under 30 is 0.20. If the proportion of readers under 30 is 0.80. What is the probability that a randomly selected male subscriber is under 30?

12. 5 x 3 = 15
13. Daily income (in Rs) of ten families of a particular place is given below. Find out GM
85, 70, 15, 75, 500, 8, 45, 250, 40, 36

14. Compute the Geometric mean from the data given below

 Marks 0-10 10-20 20-30 30-40 40-50 No. of Students 8 12 18 8 6
15. An automobile driver travels from plain to hill station 100km distance at an average speed of 30km per hour. He then makes the return trip at average speed of 20km per hour what is his average speed over the entire distance (200km)?

16. A’s scooter gives an average of 40km a litre while B’s scooter gives an average of 30km a litre . Find out the mean, if
(i) each one of them travels 120 km.
(ii) the petrol consumed by both of them is 2 litres per head.

17. Find the geometric mean of 3, 6, 24, 48

18. 4 x 5 = 20
19. A, B and C was 50% , 30% and 20% of the cars in a service station respectively. They fail to clean the glass in 5% , 7% and 3% of the cars respectively. The glass of a washed car is checked. What is the probability that the glass has been cleaned?

20. Three coins are tossed simultaneously. Consider the events A ‘three heads or three tails’, B ‘atleast two heads’ and C ‘at most two heads’ of the pairs (A, B), (A, C) and (B, C), which are independent? Which are dependent?

21. A factory has 3 machines A1, A2, A3 producing 1000, 2000, 3000 bolts per day respectively. A1 produces 1% defectives, A2 produces 1.5% and A3 produces 2% defectives. A bolt is chosen at random and found defective. What is the probability that it comes from machine A1?

22. A box contains 4 red, 6 green balls. Two balls are picked out one by one at random without replacement. What is the probability that the second is green given that the first one is green?