NCERT solution Class 11 sequences and series

NCERT Solutions

Class 11 Maths

Sequences and Series

NCERT Questions

Ex.9.1 Q.1
Ex.9.1 Q.2
Ex.9.1 Q.3
Ex.9.1 Q.4
Ex.9.1 Q.5
Ex.9.1 Q.6
Ex.9.1 Q.7
Ex.9.1 Q.8
Ex.9.1 Q.9
Ex.9.1 Q.10
Ex.9.1 Q.11
Ex.9.1 Q.12
Ex.9.1 Q.13
Ex.9.1 Q.14
Ex.9.2 Q.1
Ex.9.2 Q.2
Ex.9.2 Q.3
Ex.9.2 Q.4
Ex.9.2 Q.5
Ex.9.2 Q.6
Ex.9.2 Q.7
Ex.9.2 Q.8
Ex.9.2 Q.9
Ex.9.2 Q.10
Ex.9.2 Q.11
Ex.9.2 Q.12
Ex.9.2 Q.13
Ex.9.2 Q.14
Ex.9.2 Q.15
Ex.9.2 Q.16
Ex.9.2 Q.17
Ex.9.2 Q.18
Ex.9.3 Q.1
Ex.9.3 Q.2
Ex.9.3 Q.3
Ex.9.3 Q.4
Ex.9.3 Q.6
Ex.9.3 Q.6
Ex.9.3 Q.7
Ex.9.3 Q.8
Ex.9.3 Q.9
Ex.9.3 Q.10
Ex.9.3 Q.11
Ex.9.3 Q.12
Ex.9.3 Q.13
Ex.9.3 Q.14
Ex.9.3 Q.15
Ex.9.3 Q.16
Ex.9.3 Q.17
Ex.9.3 Q.18
Ex.9.3 Q.19
Ex.9.3 Q.20
Ex.9.3 Q.21
Ex.9.3 Q.22
Ex.9.3 Q.23
Ex.9.3 Q.24
Ex.9.3 Q.25
Ex.9.3 Q.26
Ex.9.3 Q.27
Ex.9.3 Q.28
Ex.9.3 Q.29
Ex.9.3 Q.30
Ex.9.3 Q.31
Ex.9.3 Q.32
Ex.9.4 Q.1
Ex.9.4 Q.2
Ex.9.4 Q.3
Ex.9.4 Q.4
Ex.9.4 Q.5
Ex.9.4 Q.6
Ex.9.4 Q.7
Ex.9.4 Q.8
Ex.9.4 Q.9
Ex.9.4 Q.10
Ex.Misc.Q.1
Ex.Misc.Q.2
Ex.Misc.Q.3
Ex.Misc.Q.4
Ex.Misc.Q.5
Ex.Misc.Q.6
Ex.Misc.Q.7
Ex.Misc.Q.8
Ex.Misc.Q.9
Ex.Misc.Q.10
Ex.Misc.Q.11
Ex.Misc.Q.12
Ex.Misc.Q.13
Ex.Misc.Q.14
Ex.Misc.Q.15
Ex.Misc.Q.16
Ex.Misc.Q.17
Ex.Misc.Q.18
Ex.Misc.Q.19
Ex.Misc.Q.20
Ex.Misc.Q.21
Ex.Misc.Q.22
Ex.Misc.Q.23
Ex.Misc.Q.24
Ex.Misc.Q.25
Ex.Misc.Q.26
Ex.Misc.Q.27
Ex.Misc.Q.28
Ex.Misc.Q.29
Ex.Misc.Q.30
Ex.Misc.Q.31
Ex.Misc.Q.32
Ex.15.2 Q.6
Ex.15.2 Q.7
Ex.15.2 Q.8
Ex.15.2 Q.9
Ex.15.2 Q.10
Ex.15.3 Q.1
Ex.15.3 Q.2
Ex.15.3 Q.3
Ex.15.3 Q.4
Ex.15.3 Q.5
Ex.Misc.Q.1
Ex.Misc.Q.2
Ex.Misc.Q.3
Ex.Misc.Q.4
Ex.Misc.Q.5
Ex.Misc.Q.6
Ex.Misc.Q.7

Ex.Misc.Q.5

The mean and standard deviation of 20 observations is found to be 10 and 2, respectively.

On rechecking, it was found that an observation 8 was incorrect.

Calculate the correct mean and standard deviation in each of the following cases:

(1) If wrong item is omitted.

(2) If it is replaced by 12.

(1) Number of observations (n) = 20

Incorrect mean = 10

Incorrect standard deviation = 2

Mean, x = (1 ÷ n) × Σ_i=1²⁰ x_i

=> 10 = (1 ÷ 20) × Σ_i=1²⁰ x_i

=> Σ_i=1²⁰ x_i= 200

That is, incorrect sum of observations = 200

Correct sum of observations = 200 – 8 = 192

Correct mean = (correct sum ÷ 19) = (192 ÷ 19) = 10.1

Standard deviation σ = √ [(1 ÷ n) × Σ_i=1ⁿ x_i² – (Σ_i=1ⁿ x_i)²÷ n²]

=> 2 = √ [(1 ÷ n) × incorrect Σ_i=1ⁿ xi ² – (x)²]

=> 2 = √ [(1 ÷ 20) × incorrect Σ_i=1ⁿ x_i² – (10)²]

=> 4 = (1 ÷ 20) × incorrect Σ_i=1ⁿ x_i² – 100

=> incorrect Σ_i=1ⁿ x_i² = 2080

So, correct Σ_i=1ⁿ x_i² = incorrect Σ_i=1ⁿ x_i² – 8

= 2080 – 64

= 2016

So, Correct Standard deviation = √ [{correct Σ x_i² ÷ n} – (correct mean)²]

= √ [{2016 ÷ 19} – (10.1)²]

= √ [106.1 – 102.01]

= √4.09

= 2.02

(2) When 8 is replaced by 12,

Incorrect sum of observations = 200

So, Correct sum of observations = 200 – 8 + 12 = 204

Correct mean = correct sum ÷ 20 = 204 ÷ 20 = 10.2

Standard deviation σ = √ [{(1 ÷ n) × Σ_i=1ⁿ x_i²} – {(Σ_i=1ⁿ x_i)²÷ n²}]

=> 2 = √ [(1 ÷ n) × incorrect Σ_i=1ⁿ x_i² – (x )²]

=> 2 = √ [(1 ÷ 20) × incorrect Σ_i=1ⁿ x_i² – (10)²]

=> 4 = (1 ÷ 20) × incorrect Σ_i=1ⁿ x_i² – 100

=> (1 ÷ 20) × incorrect Σ_i=1ⁿ x_i² = 104

=> incorrect Σ_i=1ⁿ x_i² = 2080

So, correct Σ_i=1ⁿ x_i² = incorrect Σ_i=1ⁿ x_i² – 8²+ 12²

= 2080 – 64 + 144

= 2160

So, Correct Standard deviation = √ [(correct Σ x_i²÷ n) – (correct mean)²]

= √ [(2160 ÷ 20) – (10.2)²]

= √ [108 – 104.04]

= √3.96

= 1.98

Sequences and Series Class 11 Maths NCERT Chapter 8 NCERT Solutions

Solving NCERT textbook questions of Sequences and Series Class 11 Maths NCERT Chapter 8 is a crucial step to gauge your understanding of the concepts. It provides you with an opportunity to assess your grasp of the material after learning each chapter. We have already provided solutions to all the exercises in the NCERT textbook of Class 11 Maths Sequences and Series, available in various formats such as video, text, and downloadable PDFs. If you need assistance with any of the NCERT questions or any other academic topics, feel free to ask in the “Ask Questions” section of LearnoHub.com.

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Using the NCERT solutions module effectively can significantly enhance your learning experience and understanding of the subject matter. Here's a step-by-step guide on how to make the most out of the NCERT solutions:

Attempt to Solve Yourself: Before looking at the solution, try to solve or answer the question independently. This practice will help you test your knowledge and problem-solving skills.
Match with Our Solution: After attempting the question, compare your result and approach with the provided NCERT solution. This step allows you to identify any mistakes or gaps in your understanding.
Refer to Solution Video (if needed): If you encounter difficulty or are unable to solve a question, you can refer to the NCERT solution video on Sequences and Series Class 11 Maths NCERT Chapter 8 to get a step-by-step explanation of the correct approach. Pay attention to the reasoning and methodology used in the video.
Solve Again Yourself: Once you've understood the solution, attempt to solve the question again by yourself. Repetition and practice solidify your understanding of the concepts and improve retention.
Avoid Memorization: Focus on understanding the underlying principles and concepts behind each solution. Avoid simply memorizing the solutions, as this may hinder your ability to apply the knowledge in different contexts.
Attempt All Questions: Make an effort to attempt all the questions provided in the NCERT textbook. This comprehensive practice will help you cover the entire syllabus and reinforce your understanding across various topics. You may refer Class 11 Maths Sequences and Series Online Test on LearnoHub.com.
Review and Revise: Regularly review the concepts and solutions you've learned. Revise your notes and practice regularly to retain the knowledge effectively. You may refer Sequences and Series Class 11 Maths Notes.
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By following these steps and actively engaging with the NCERT solutions module of Class 11 Maths Sequences and Series NCERT Chapter 8, you can improve your learning outcomes, develop a better grasp of the subject, and perform well in exams and other academic assessments. Remember that consistent practice, understanding, and application of knowledge are key to academic success.

NCERT solutions of Sequences and Series Class 11 Maths - all questions of all exercises are solved. Q. No. 1, 2, 3, and so on. Complete explanation and detailed solution makes them the best videos for Class 11 Maths Sequences and Series NCERT solutions.