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Finding the Fourth Proportional to 781.89, 1,171.28 and 521.12

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Solution

The fourth proportional to 781.89, 1,171.28 and 521.12 is: 780.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.89 : 1,171.28 = 521.12 : x
  2. Step 2: Convert to fraction form
    781.89/1,171.28 = 521.12/x
  3. Step 3: Cross multiply
    781.89x = 1,171.28 × 521.12
  4. Step 4: Simplify right side
    781.89x = 610,372.88
  5. Step 5: Solve for x
    x = 610,372.88/781.89
  6. Step 6: Final answer
    x = 780.64

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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.