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Finding the Fourth Proportional to 687.21, 1,031.17 and 317.02

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Solution

The fourth proportional to 687.21, 1,031.17 and 317.02 is: 475.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.21 : 1,031.17 = 317.02 : x
  2. Step 2: Convert to fraction form
    687.21/1,031.17 = 317.02/x
  3. Step 3: Cross multiply
    687.21x = 1,031.17 × 317.02
  4. Step 4: Simplify right side
    687.21x = 326,894.77
  5. Step 5: Solve for x
    x = 326,894.77/687.21
  6. Step 6: Final answer
    x = 475.68

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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.