Question

If five G.M.’s are inserted between 486 and 2/3 then fourth G.M. will be.

• A. 4
• B. 6
• C. 12
• D. – 6

Answer 1

Answer: (B)

6

Answer 2

Let $G _ { 1 } , G _ { 2 } , G _ { 3 } , G _ { 4 } , G _ { 5 }$ be the G.M.’s are inserted between 486 and 2/3. So total terms are 7.

$T _ { n } = a r ^ { n - 1 }$ ⇒ 2/3 = 486$( r ) ^ { 6 }$ $\Rightarrow r = 1 / 3$

Hence 4^th G.M. will be, $T _ { 5 } = a r ^ { 4 } = 486 ( 1 / 3 ) ^ { 4 } = 6$.