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Finding the Fourth Proportional to 691.20, 1,038.40 and 475.20

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Solution

The fourth proportional to 691.20, 1,038.40 and 475.20 is: 713.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.20 : 1,038.40 = 475.20 : x
  2. Step 2: Convert to fraction form
    691.20/1,038.40 = 475.20/x
  3. Step 3: Cross multiply
    691.20x = 1,038.40 × 475.20
  4. Step 4: Simplify right side
    691.20x = 493,447.68
  5. Step 5: Solve for x
    x = 493,447.68/691.20
  6. Step 6: Final answer
    x = 713.90

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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.