If 20 men can build a water fountain 56 metres long in 42 days, what length of a similar water fountain can be built by 35 men in 3 days?	Pick one:  A) 3 m  B) 4 m  C) 7 m  D) 9 m  E) 10 m
Explanation :   Let the required length be x metres   More men, More length built (Direct Proportion)   Less days, Less length built (Direct Proportion)   Men 20: 35   Days 42: 3 : : 56 : x   Therefore (20 x 42 x x)=(35 x 3 x 56)   x=(35 x 3 x 56)/840=7   Hence, the required length is 7 m.   Answer : 7 m
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If 20 men can build a water fountain 56 metres long in 42 days, what length of a similar water fountain can be built by 35 men in 3 days?