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Finding the Fourth Proportional to 1,387.90, 2,081.86 and 414.28

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Solution

The fourth proportional to 1,387.90, 2,081.86 and 414.28 is: 621.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.90 : 2,081.86 = 414.28 : x
  2. Step 2: Convert to fraction form
    1,387.90/2,081.86 = 414.28/x
  3. Step 3: Cross multiply
    1,387.90x = 2,081.86 × 414.28
  4. Step 4: Simplify right side
    1,387.90x = 862,472.96
  5. Step 5: Solve for x
    x = 862,472.96/1,387.90
  6. Step 6: Final answer
    x = 621.42

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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.