Question 121824
ASSUMING ALL SPHERES ARE THE SAME THICKNESS THEN:
AREA=PIR^2=3.14*2^2=3.14*4=12.56 MM^2
AREA=3.14*3^2=3.14*9=28.26 MM^2
AREA=3.14*4^2=3.14*16=50.24 MM^2
TOTAL AREA=12.56+28.26+50.24=91.06 MM^2
91.06=3.14R^2
R^2=91.06/3.14
R^2=29
R=SQRT29 
R=5.385 MM IS THE NEW RADIUS.