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Finding the Fourth Proportional to 859.60, 1,289.40 and 640.90

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Solution

The fourth proportional to 859.60, 1,289.40 and 640.90 is: 961.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.60 : 1,289.40 = 640.90 : x
  2. Step 2: Convert to fraction form
    859.60/1,289.40 = 640.90/x
  3. Step 3: Cross multiply
    859.60x = 1,289.40 × 640.90
  4. Step 4: Simplify right side
    859.60x = 826,376.46
  5. Step 5: Solve for x
    x = 826,376.46/859.60
  6. Step 6: Final answer
    x = 961.35

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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.