CBSE - Statistics

1 Statistics 

The frequency distribution of marks obtained by 28 students in a test carrying 40 marks is given below

If the mean of the above data is 20, then the difference between x and y is 
(1) 3
(2) 2
(3) 1
(4) 0

2 Statistics 

If the median of the data x1,x2,x3,x4,x5,x6,x7,x8 is α and x1<x2<x3<x4<x5<x6<x7<x8, then the median of x3,x4,x5,x6 is

(1) α
(2) α / 2
(3) α / 3
(4) α / 4

3 Statistics 

A school has 20 teachers, one of them retires at the age of 60  years and a new teacher replaces him, this  change reduces the average  age of the staff by 2 years,  the age of new teacher is 

(1) 28 years
(2) 25 years
(3) 20 years
(4) 18 years

4 Statistics 

The mean yearly salary of an employee of acompany was Rs. 20,000. If the mean yearly salaries of male and female employees were Rs. 20800 and Rs. 16800  respectively, then the percentages of males and females employed in the company respectively are

(1) 80% and 20%
(2) 70% and 30%
(3) 55% and 45%
(4) 50% and 50%

5 Statistics 

Following table gives the number of trees planted by the students in a school on ' Environment Day, Observe the table and find mode of the trees planted by the students.

1) 80
2) 50
3) 45
4) 35

6 Statistics 

The mean age of a combined group of men and women is 25 years. If the mean age of the group of men is 26 and that of the group of women is 21, then the percentage of men and women in the group is

(1) 60, 40
(2) 80, 20
(3) 20, 80
(4) 40, 60

7 Statistics 

When 10  is subtracted from all the observations, the mean is reduced to 60%  of its value. If 5 is added to all the observations, then the mean will be

(1) 25
(2) 30 
(3) 60
(4) 65 

8 Statistics 

The coefficient of range of a set of data is given to be 18. Then the ratio of the maximum value in the data to the minimum value is:

(1) 8 / 1
(2) 9 / 8 
(3) 9 / 7
(4) 8 / 7

9 Statistics 

The median of first 12 prime numbers is : 

(1) 13  
(2) 14 
(3) 15 
(4) 17

10 Statistics 

The mean and median of the data x,y,z are 50 and 35respectively, where x<y<z. If z−x=55, then the value of (y−x) is

(1) 8
(2) 7
(3) 3
(4) 5