Question 6 - CBSE Class 10 Sample Paper for 2026 Boards - Maths Basic - Solutions of Sample Papers for Class 10 Boards

Last updated at July 27, 2026 by Teachoo

If 1 + 2 + 3 + 4 +⋯+ 50 = 25k, then k = (A) 50 (B) 51 (C) 49 (D) 26 - CBSE Class 10 Sample Paper for 2026 Boards - Maths Basic

part 2 - Question 6 - CBSE Class 10 Sample Paper for 2026 Boards - Maths Basic - Solutions of Sample Papers for Class 10 Boards - Class 10

part 3 - Question 6 - CBSE Class 10 Sample Paper for 2026 Boards - Maths Basic - Solutions of Sample Papers for Class 10 Boards - Class 10

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Transcript

Question 6 If 1 + 2 + 3 + 4 + … + 50 = 25k, then k = (A) 50 (B) 51 (C) 49 (D) 26 Here we are given AP 1, 2, 3, 4, …. 50 And, Sum of AP = 25k Let’s find Sum using AP formula Here, First term = a = 1 Common difference = d = 2 – 1 = 1 Last term = an = l = 50 Total terms = n = 50 Note: Number of terms between two numbers a & b, if a and b are included is (b – a) + 1. Example here: 50 – 1 + 1 = 50 Now, we know that Sum of n terms = 𝑛/2(𝑎+𝑙) Putting Sum = 25k, n = 50, a = 1, l = 5- 25k=50/2(1+50) 25k=25 × 51 k=(25 × 51)/25 𝐤=𝟓𝟏 So, correct answer is (b)

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