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Finding the Fourth Proportional to 487.28, 670.56 and 421.40

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Solution

The fourth proportional to 487.28, 670.56 and 421.40 is: 579.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    487.28 : 670.56 = 421.40 : x
  2. Step 2: Convert to fraction form
    487.28/670.56 = 421.40/x
  3. Step 3: Cross multiply
    487.28x = 670.56 × 421.40
  4. Step 4: Simplify right side
    487.28x = 282,573.98
  5. Step 5: Solve for x
    x = 282,573.98/487.28
  6. Step 6: Final answer
    x = 579.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.