In This Post we are providing Chapter-15 STATISTICS NCERT MOST IMPORTANT QUESTIONS for Class 11 MATHS which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.
NCERT MOST IMPORTANT QUESTIONS ON STATISTICS
1. In a test with a maximum marks 25, eleven students scored 3,9,5,3,12,10,17,4,7,19,21 marks respectively. Calculate the range.
Ans. The marks can be arranged in ascending order as 3,3,4,5,7,9,10,12,17,19,21.
Range = maximum value – minimum value
=21-3
= 18
2. Coefficient of variation of two distributions is 70 and 75, and their standard deviations are 28 and 27 respectively what are their arithmetic mean?
Ans. Given C.V (first distribution) = 70
Standard deviation =
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image001.png)
C.V
=
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image004.png)
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image005.png)
Similarly for second distribution
C.V
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image007.png)
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image008.png)
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image009.png)
3. Write the formula for mean deviation.
Ans.MD
4. Write the formula for variance
Ans. Variance
5. Find the median for the following data.
579101215
862226
Ans.
![]() | 5 | 7 | 9 | 10 | 12 | 15 |
![]() | 8 | 6 | 2 | 2 | 2 | 6 |
![]() | 8 | 14 | 16 | 18 | 20 | 26 |
Median is the average of 13th and 14th item, both of which lie in the c.f 14
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image016.png)
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image017.png)
6. Write the formula of mean deviation about the median
Ans.
7. Find the rang of the following series 6,7,10,12,13,4,8,12
Ans. Range = maximum value – minimum value
= 113-4
=9
8. Find the mean of the following data 3,6,11,12,18
Ans. Mean =
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image020.png)
9. Express in the form of a + ib (3i-7) + (7-4i) – (6+3i) + i23
Ans. Let
Z =
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image022.png)
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image023.png)
10. Find the conjugate of
Ans.
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image026.png)
11. Solve for x and y, 3x + (2x-y) i= 6 – 3i
Ans.3x = 6
x = 2
2x – y = – 3
2 × 2 – y = – 3
– y = – 3 – 4
y = 7
12. Find the value of 1+i2 + i4 + i6 + i8 + —- + i20
Ans.
13. Multiply 3-2i by its conjugate.
Ans. Let z = 3 – 2i
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image028.png)
14. Find the multiplicative inverse 4 – 3i.
Ans. Let z = 4 – 3i
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image029.png)
15. Express in term of a + ib
Ans.
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image032.png)
![](https://cdn1.coolgyan.org/images/static/impq/11/maths/ch15/1m/image033.png)