✓ Board-verified
Mathematics · 2022 · 2 marks
CBSE 2022 · Region 4 · Set 2 · Q4
If the first term of an A.P. is 5, the last term is 15 and the sum of first n terms is 30, then find the value of n.
If the first term of an A.P. is $\displaystyle 5$, the last term is $\displaystyle 15$ and the sum of first n terms is $\displaystyle 30$ , then find the value of n .
Marking-scheme solution
$\displaystyle \begin{array}{l}a=5, \text { last term } l=15
S_{n}=30 \Rightarrow \frac{n}{2}(a+l)=30
\Rightarrow \frac{n}{2}(5+15)=30 \Rightarrow n=3\end{array}$
All Arithmetic Progressions questions2022 question paperNCERT solutions: Arithmetic ProgressionsPractice Arithmetic Progressions →
More from Arithmetic Progressions
- Prerna saves ₹ 32 during the first month, ₹ 36 in the second month and ₹ 40 in the third month. If she continues to save in this manner, in how many…2023
- In an A.P., if the first term (a)=-16 and the common difference (d)=-2, then the sum of first 10 terms is:2024
- The next term of the A.P.: √6, √24, √54 is:2023
- The common difference of the A.P. whose n^th term is given by a_n=3 n+7, is:2023
- If the sum of the first 14 terms of an A.P. is 1050 and the first term is 10, then find the 20^th term and the n^th term. OR The first term of an…2024
- Find the sum of all 3-digit natural numbers which are divisible by 11.2025
- In an A.P., the first term is 32 and the last term is - 10. If the common difference is -2, then find the number of terms and their sum. OR Find the…2026
- The next (4^th ) term of the A.P. √18, √50, √98, … is:2024
CBSE Class 10 Mathematics past-paper question from the 2022 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.