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Finding the Fourth Proportional to 939.12, 1,408.80 and 426

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Solution

The fourth proportional to 939.12, 1,408.80 and 426 is: 639.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.12 : 1,408.80 = 426 : x
  2. Step 2: Convert to fraction form
    939.12/1,408.80 = 426/x
  3. Step 3: Cross multiply
    939.12x = 1,408.80 × 426
  4. Step 4: Simplify right side
    939.12x = 600,148.80
  5. Step 5: Solve for x
    x = 600,148.80/939.12
  6. Step 6: Final answer
    x = 639.05

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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.