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Finding the Fourth Proportional to 487.40, 672.69 and 389.90

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Solution

The fourth proportional to 487.40, 672.69 and 389.90 is: 538.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    487.40 : 672.69 = 389.90 : x
  2. Step 2: Convert to fraction form
    487.40/672.69 = 389.90/x
  3. Step 3: Cross multiply
    487.40x = 672.69 × 389.90
  4. Step 4: Simplify right side
    487.40x = 262,281.83
  5. Step 5: Solve for x
    x = 262,281.83/487.40
  6. Step 6: Final answer
    x = 538.12

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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.