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Finding the Fourth Proportional to 687.80, 1,031.52 and 322.40

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Solution

The fourth proportional to 687.80, 1,031.52 and 322.40 is: 483.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.80 : 1,031.52 = 322.40 : x
  2. Step 2: Convert to fraction form
    687.80/1,031.52 = 322.40/x
  3. Step 3: Cross multiply
    687.80x = 1,031.52 × 322.40
  4. Step 4: Simplify right side
    687.80x = 332,562.05
  5. Step 5: Solve for x
    x = 332,562.05/687.80
  6. Step 6: Final answer
    x = 483.52

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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.