Question

If the sum of n terms of two Arithmetic series are in the ratio (7n + 1) : (4n + 27), then their 11^th terms are in the ratio –

• A. ¾
• B. 4/3
• C. 78/61
• D. None

Answer 1

Answer: (B)

4/3

Answer 2

$\frac { \mathrm { S } _ { \mathrm { n } } } { \mathrm { S } _ { \mathrm { n } } ^ { \prime } } = \frac { 7 \mathrm { n } + 1 } { 4 \mathrm { n } + 27 } \xrightarrow { \mathrm { n } = 2.11 - \mathrm { l } = 21 }$

= $\frac { 7 \times 21 + 1 } { 4 \times 21 + 27 } = \frac { 148 } { 111 } = \frac { 4 } { 3 }$