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Finding the Fourth Proportional to 640.80, 961.20 and 559.80

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Solution

The fourth proportional to 640.80, 961.20 and 559.80 is: 839.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    640.80 : 961.20 = 559.80 : x
  2. Step 2: Convert to fraction form
    640.80/961.20 = 559.80/x
  3. Step 3: Cross multiply
    640.80x = 961.20 × 559.80
  4. Step 4: Simplify right side
    640.80x = 538,079.76
  5. Step 5: Solve for x
    x = 538,079.76/640.80
  6. Step 6: Final answer
    x = 839.70

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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.