question_answer

A field is 125 m long and 15 m wide. A tank \[10\,\,\text{m}\times 7.5\,\,\text{m}\times 6\,\,\text{m}\] was dug in it and the Earth, thus dug out was spread equally on the remaining field. The level of the field thus raised is equal to which one of the following?

A) 15 cm

B)  20 cm

C)  25 cm

D)  30 cm

Correct Answer: C

Solution :

Area of tank, BCDE\[=10\times 7.5=75\,\,{{\text{m}}^{2}}\] Area of remaining field ABEDFGA \[=125\times 15-75\] =1800 sq m Volume of Earth dug \[=10\times 7.5\times 6=450\,\,\text{cu}\,\,\text{m}\] By given condition, \[1800\times h=450\] \[\Rightarrow \]   \[h=\frac{1}{4}\,\,\text{m}=\frac{1}{4}\times 100\,\,\text{cm}=25\,\,\text{cm}\]