Area Centroids of Composite Shapes

Q. From a circular disc of radius 'R' having a centre A, a smaller disc of radius '0.5 R' and centre B, is cut out, such that the point A lies on its circumference, as shown in figure. The centre of gravity of the remaining portion of the larger disc (shaded area) is on the line joining the centres A and B at a distance 'x' from centre A, where 'x' is

1. 0.5 R
2. R/6
3. 3R/4
4. R/3