Find the sum of the AP (7, 12, 17, ..., 82).
Answer and explanation
Correct answer: 712
The governing concept is the sum of the first n terms of an arithmetic progression. Here, the first term is a = 7, the common difference is d = 5, and the last term is 82. Using 82 = 7 + (n − 1)5 gives n = 16. Therefore, Sₙ = n/2(first term + last term) = 16/2 × (7 + 82) = 8 × 89 = 712. Hence option B is correct; the other values result from an incorrect term count or sum.
Frequently asked questions
What is the correct answer to this question?
712
Why is this the correct answer?
The governing concept is the sum of the first n terms of an arithmetic progression. Here, the first term is a = 7, the common difference is d = 5, and the last term is 82. Using 82 = 7 + (n − 1)5 gives n = 16. Therefore, Sₙ = n/2(first term + last term) = 16/2 × (7 + 82) = 8 × 89 = 712. Hence option B is correct; the other values result from an incorrect term count or sum.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Finding the sum of the first $n$ terms of an AP.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
