Use app×
Join Bloom Tuition
One on One Online Tuition
JEE MAIN 2025 Foundation Course
NEET 2025 Foundation Course
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
57 views
in Statistics by (240k points)
closed by
The mean of first n natural numbers is 5. Find n?
1. 8
2. 9
3. 11
4. 10

1 Answer

0 votes
by (238k points)
selected by
 
Best answer
Correct Answer - Option 2 : 9

Concept:

Mean: It is sum of all observations upon number of observations.

If x1, x2, x3, …., xn are the observations, then mean is given as

\(\rm \bar{X} = \frac{sum\ of\ observations}{number\ of\ observations}\)

\(\rm \bar{X}= \frac{x_{1}+x_{2}+...+x_{n}}{n}\)

Sum of first n natural number \(\rm = \frac{n(n+1)}{2}\)

 

Calculation:

We have X̅ = 5

Sum of first n natural number \(\rm = \frac{n(n+1)}{2}\)

Mean of first n natural number  \(\rm = \frac{\frac{n(n+1)}{2}}{n}\)

\(\rm ⇒ 5 = \frac{(n+1)}{2}\)

⇒ 10 = n + 1

⇒ n = 9

No related questions found

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...