Three particles of masses $50 \mathrm {~g} , 100 \mathrm {~g}$ and 150 g are placed at the vertices of an equilateral triangle of side 1 m (as shown in the figure). The $( \mathrm { x } , \mathrm { y } )$ coordinates of the centre of mass will be:
(1) $\left( \frac { 7 } { 12 } \mathrm {~m} , \frac { \sqrt { 3 } } { 4 } \mathrm {~m} \right)$
(2) $\left( \frac { 7 } { 12 } \mathrm {~m} , \frac { \sqrt { 3 } } { 8 } \mathrm {~m} \right)$
(3) $\left( \frac { \sqrt { } 3 } { 4 } \mathrm {~m} , \frac { 5 } { 12 } \mathrm {~m} \right)$
(4) $\left( \frac { \sqrt { 3 } } { 8 } \mathrm {~m} , \frac { 7 } { 12 } \mathrm {~m} \right)$