Saturday, 25 February 2012

STATISTICS (CLASS 9)


MEASURES OF CENTRAL TENDENCY

1. Find the median of the following data :61,68,56,72,23,84,76,48,99,58. If 58 is replaced by 85 find the new median ?

2. The median of the observation arranged in ascending order is 24. Find the value of x :

 11,  12, 14, 18, x+2, x+4, 30, 32, 35, 41.

3. Determine the median of 24, 23, a, a-1, 12, 16, where a is the mean of 10,20,30,40, and 50.

4. If the mean of 5, 8, 9, x  and 14 is 10 ,Find the value of x ?

5. The mean of 16 numbers is 8. If 2 is added to every number, what will be the new mean?

6. The mean of 20 numbers is 41. If 6 is subtracted to every number, what will be the new mean?

7. The mean of 100 numbers is 24. If 6 is added to every number and then multiplied by 2.5. what will be the new mean?

8. The mean of certain group of observations is 150. what will be the new mean, if the value of each observation is :

(a) decreased by 26%

(b) multiplied by 2.5

(c) divided by 3.

9. The sum of the deviations of a set of n values x1 ,x2 ,x3,..............xn measured from 50 is -10b and the sum of deviations of the values from 46 is 70. Find the value of n and the mean .

10. A ship sails out to an island at the rate of 16km/h and sails back to the starting point at 20km/h. Find the average speed of the boat during the whole journey.

11. Nine persons went to a hotel for taking the meals . Eight of them spends Rs 12 each on their meals and the ninth person spent Rs 8 more than the average expenditure of all the nine. What was the total monthly spent by them ?

12. The average score of boys in an examination of a school as 71 and that of the girls is 73. The average score of the school in an examination is 71.8. Find the ratio of the number of boys to the number of girls that appeared in an examination .

13. The mean heights of 10 students was 153 cm .But later on it was discovered that 151 cm was wrongly read as 141 cm. Find the correct mean .

14. Find the mean median and mode of the following data :

14, 25, 14, 28, 18, 17, 18, 14, 23, 22, 14, 18.

      



  

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