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Finding the Fourth Proportional to 691.34, 1,036.20 and 280.40

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Solution

The fourth proportional to 691.34, 1,036.20 and 280.40 is: 420.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.34 : 1,036.20 = 280.40 : x
  2. Step 2: Convert to fraction form
    691.34/1,036.20 = 280.40/x
  3. Step 3: Cross multiply
    691.34x = 1,036.20 × 280.40
  4. Step 4: Simplify right side
    691.34x = 290,550.48
  5. Step 5: Solve for x
    x = 290,550.48/691.34
  6. Step 6: Final answer
    x = 420.27

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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.