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Finding the Fourth Proportional to 2,640, 3,960 and 816

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Solution

The fourth proportional to 2,640, 3,960 and 816 is: 1,224

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,640 : 3,960 = 816 : x
  2. Step 2: Convert to fraction form
    2,640/3,960 = 816/x
  3. Step 3: Cross multiply
    2,640x = 3,960 × 816
  4. Step 4: Simplify right side
    2,640x = 3,231,360
  5. Step 5: Solve for x
    x = 3,231,360/2,640
  6. Step 6: Final answer
    x = 1,224

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.