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Finding the Fourth Proportional to 426.70, 639.57 and 289.78

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Solution

The fourth proportional to 426.70, 639.57 and 289.78 is: 434.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.70 : 639.57 = 289.78 : x
  2. Step 2: Convert to fraction form
    426.70/639.57 = 289.78/x
  3. Step 3: Cross multiply
    426.70x = 639.57 × 289.78
  4. Step 4: Simplify right side
    426.70x = 185,334.59
  5. Step 5: Solve for x
    x = 185,334.59/426.70
  6. Step 6: Final answer
    x = 434.34

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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.