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Finding the Fourth Proportional to 913.20, 1,369.90 and 426.40

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Solution

The fourth proportional to 913.20, 1,369.90 and 426.40 is: 639.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    913.20 : 1,369.90 = 426.40 : x
  2. Step 2: Convert to fraction form
    913.20/1,369.90 = 426.40/x
  3. Step 3: Cross multiply
    913.20x = 1,369.90 × 426.40
  4. Step 4: Simplify right side
    913.20x = 584,125.36
  5. Step 5: Solve for x
    x = 584,125.36/913.20
  6. Step 6: Final answer
    x = 639.65

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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.