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Finding the Fourth Proportional to 939.68, 1,408.29 and 691.72

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Solution

The fourth proportional to 939.68, 1,408.29 and 691.72 is: 1,036.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.68 : 1,408.29 = 691.72 : x
  2. Step 2: Convert to fraction form
    939.68/1,408.29 = 691.72/x
  3. Step 3: Cross multiply
    939.68x = 1,408.29 × 691.72
  4. Step 4: Simplify right side
    939.68x = 974,144.17
  5. Step 5: Solve for x
    x = 974,144.17/939.68
  6. Step 6: Final answer
    x = 1,036.68

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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.