HOTS Mathematics Primary 5 Volume

A rectangular drainage tank at an HDB estate measures 75 cm long and 40 cm wide. Water fills the tank to a height of 20 cm. A solid metal block measuring 30 cm × 20 cm × 15 cm is then fully submerged in the water. What is the new height of the water after the block is submerged?

A 23 cm
B 35 cm
C 26 cm
D 22 cm
Show Worked Solution

Worked Solution

Step 1: Find the volume of water initially in the tank: Volume of water = 75 × 40 × 20 = 60 000 cm³ Step 2: Find the volume of the solid metal block: Volume of block = 30 × 20 × 15 = 9000 cm³ Step 3: Find the total volume (water + block) in the tank: Total volume = 60 000 + 9000 = 69 000 cm³ Step 4: Find the new height of water using the full tank base area: Base area of tank = 75 × 40 = 3000 cm² New height = 69 000 ÷ 3000 = 23 cm

Correct answer: 23 cm

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