In a gravity dam the total overturning moment about toe and total resisting moment about toe are 1 × 105 ton - m & 2 × 105 ton-m respectively. Base width of dam is 50 m and total vertical force above base is 5000 ton, then the eccentricity of loading is ________
1
20 m
2
15 m
3
10 m
4
5 m