Question

Find sum of 11 terms of on A.P. whose middle term = 30 is –

• A. 320
• B. 330
• C. 340
• D. 350

Answer 1

Answer: (B)

330

Answer 2

$\frac { 11 } { 2 }$ (a₁ + a₁₁) = $\frac { 11 } { 2 }$ (2 × middle term)

$\frac { 11 } { 2 }$ × (2 × 30) = 330