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Finding the Fourth Proportional to 1,280.70, 1,921.34 and 415

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Solution

The fourth proportional to 1,280.70, 1,921.34 and 415 is: 622.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.70 : 1,921.34 = 415 : x
  2. Step 2: Convert to fraction form
    1,280.70/1,921.34 = 415/x
  3. Step 3: Cross multiply
    1,280.70x = 1,921.34 × 415
  4. Step 4: Simplify right side
    1,280.70x = 797,356.10
  5. Step 5: Solve for x
    x = 797,356.10/1,280.70
  6. Step 6: Final answer
    x = 622.59

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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.