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Finding the Fourth Proportional to 1,280.71, 1,921.02 and 415

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Solution

The fourth proportional to 1,280.71, 1,921.02 and 415 is: 622.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.71 : 1,921.02 = 415 : x
  2. Step 2: Convert to fraction form
    1,280.71/1,921.02 = 415/x
  3. Step 3: Cross multiply
    1,280.71x = 1,921.02 × 415
  4. Step 4: Simplify right side
    1,280.71x = 797,223.30
  5. Step 5: Solve for x
    x = 797,223.30/1,280.71
  6. Step 6: Final answer
    x = 622.49

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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.