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Finding the Fourth Proportional to 487.90, 673.38 and 390.40

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Solution

The fourth proportional to 487.90, 673.38 and 390.40 is: 538.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    487.90 : 673.38 = 390.40 : x
  2. Step 2: Convert to fraction form
    487.90/673.38 = 390.40/x
  3. Step 3: Cross multiply
    487.90x = 673.38 × 390.40
  4. Step 4: Simplify right side
    487.90x = 262,887.55
  5. Step 5: Solve for x
    x = 262,887.55/487.90
  6. Step 6: Final answer
    x = 538.81

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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.