2)3. 14×0.4? × 50× 7.8 =195.936 ≈196 (kg)

3)3. 14×(4÷2)? × 5× 0.69 = 43.332kg.

4)3. 14×(3 1.4÷3. 14÷2)? × 6 = 47 1 (cubic centimeter)

5)3. 14×(8÷2)? × 6× 600 = 180864 (kg) = 180.864 (ton)

So it can't hold 200 tons of corn.