A rectangular sump of dimensions 6 m x 5 m x 4 m is to be built by using bricks to make the outer dimension 6.2 m x 5.2 x 4.2 m. Approximately how many bricks of size 20 cm x 10 cm x 5 cm are required to build the sump for storing water?

To find the number of bricks required, we need to calculate the volume of the walls of the sump and divide it by the volume of a single brick. Step 1: Calculate the External Volume External dimensions are 6.2 m, 5.2 m, and 4.2 m. External Volume = 6.2 x 5.2 x 4.2 = 135.408 cubic meters. Step 2: Calculate the Internal Volume Internal dimensions are 6 m, 5 m, and 4 m. Internal Volume = 6 x 5 x 4 = 120 cubic meters. Step 3: Calculate the Volume of the Walls Wall Volume = External Volume minus Internal Volume Wall Volume = 135.408 minus 120 = 15.408 cubic meters. Step 4: Calculate the Volume of one Brick Brick dimensions are 20 cm x 10 cm x 5 cm. Convert these to meters: 0.2 m x 0.1 m x 0.05 m. Brick Volume = 0.2 x 0.1 x 0.05 = 0.001 cubic meters. Step 5: Calculate the Number of Bricks Number of bricks = Volume of Walls divided by Volume of one Brick Number of bricks = 15.408 divided by 0.001 = 15408. The closest approximate value among the options is 15000. Therefore, Option C is the correct answer.