The figure is not drawn to scale. Two balls, S and T, turn and move along the line UV in opposite directions. The radius of S is 40 m. The ratio of the diameter of Ball S to that of Ball T is 7 : 3. If Ball S turns 10 rounds and Ball T turns 3 rounds, how far apart are the centres of the balls? (Take π = 3.14)
Diameter of S
= 40 x 2 
= 80 m

Circumference of S
= 3.14 x 80
= 251.2 m

Diameter of T
= 80 x ⁷₃
= 186.66666666667 m

Circumference of T
= 3.14 x 186.66666666667
= 586.13333333334 m

Distance travelled by S
= 251.2 x 10
= 2512 m

Distance travelled by T
= 586.13333333334 x 3
= 1758.4 m

Total distance travelled
= 2512 + 1758.4
= 4270.4 m

Answer(s): 4270.4 m