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Finding the Fourth Proportional to 487.96, 674.04 and 390.40

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Solution

The fourth proportional to 487.96, 674.04 and 390.40 is: 539.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    487.96 : 674.04 = 390.40 : x
  2. Step 2: Convert to fraction form
    487.96/674.04 = 390.40/x
  3. Step 3: Cross multiply
    487.96x = 674.04 × 390.40
  4. Step 4: Simplify right side
    487.96x = 263,145.22
  5. Step 5: Solve for x
    x = 263,145.22/487.96
  6. Step 6: Final answer
    x = 539.28

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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.