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Finding the Fourth Proportional to 781.12, 1,078.17 and 515.76

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Solution

The fourth proportional to 781.12, 1,078.17 and 515.76 is: 711.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.12 : 1,078.17 = 515.76 : x
  2. Step 2: Convert to fraction form
    781.12/1,078.17 = 515.76/x
  3. Step 3: Cross multiply
    781.12x = 1,078.17 × 515.76
  4. Step 4: Simplify right side
    781.12x = 556,071.57
  5. Step 5: Solve for x
    x = 556,071.57/781.12
  6. Step 6: Final answer
    x = 711.89

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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.