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Finding the Fourth Proportional to 781.32, 1,078.11 and 501.61

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Solution

The fourth proportional to 781.32, 1,078.11 and 501.61 is: 692.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.32 : 1,078.11 = 501.61 : x
  2. Step 2: Convert to fraction form
    781.32/1,078.11 = 501.61/x
  3. Step 3: Cross multiply
    781.32x = 1,078.11 × 501.61
  4. Step 4: Simplify right side
    781.32x = 540,790.76
  5. Step 5: Solve for x
    x = 540,790.76/781.32
  6. Step 6: Final answer
    x = 692.15

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.