圆锥的体积=圆锥底面积*高*1/3 即V=1/3πr^2*h
稻谷的体积V=3.14*1.5^2*1.8*1/3*1/4=1.0975(立方米)
则这对稻谷的重量M=725*1.0975=768.31875(千克)
725×(3.14×1.5×1.5×1/4×1.8×1/3)
=725×1.05975
=768.31875千克
2.4X4÷3.14÷2=240/157米
1/3X3.14X240/157X240/157X1.57X1/4X725
=96/157X1.57X725
=0.96X725
=696千克