Q62. If the sum of the series $\frac { 1 } { 1 \cdot ( 1 + \mathrm { d } ) } + \frac { 1 } { ( 1 + \mathrm { d } ) ( 1 + 2 \mathrm {~d} ) } + \ldots + \frac { 1 } { ( 1 + 9 \mathrm {~d} ) ( 1 + 10 \mathrm {~d} ) }$ is equal to 5 , then 50 d is equal to :
(1) 10
(2) 5
(3) 15
(4) 20
Q62. If the sum of the series $\frac { 1 } { 1 \cdot ( 1 + \mathrm { d } ) } + \frac { 1 } { ( 1 + \mathrm { d } ) ( 1 + 2 \mathrm {~d} ) } + \ldots + \frac { 1 } { ( 1 + 9 \mathrm {~d} ) ( 1 + 10 \mathrm {~d} ) }$ is equal to 5 , then 50 d is equal to :\\
(1) 10\\
(2) 5\\
(3) 15\\
(4) 20