Tip:A–D to answerE for explanationV for videoS to reveal answer
The mean of first n natural numbers is equal to 3n+7, then n is equal to:
- A.
9
- B.
10
- C.
11
(Correct Answer) - D.
12
Explanation
1. Formula for the sum of first n natural numbers:
2. Formula for the mean of first n natural numbers:
Mean=nSum=n2n(n+1)=2n+1
3. Equating the given mean with the formula:
4. Solving for n:
Correct Option: (c) 11
Explanation
1. Formula for the sum of first n natural numbers:
2. Formula for the mean of first n natural numbers:
Mean=nSum=n2n(n+1)=2n+1
3. Equating the given mean with the formula:
4. Solving for n:
Correct Option: (c) 11
