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Finding the Fourth Proportional to 781.34, 1,171.10 and 642.84

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Solution

The fourth proportional to 781.34, 1,171.10 and 642.84 is: 963.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.34 : 1,171.10 = 642.84 : x
  2. Step 2: Convert to fraction form
    781.34/1,171.10 = 642.84/x
  3. Step 3: Cross multiply
    781.34x = 1,171.10 × 642.84
  4. Step 4: Simplify right side
    781.34x = 752,829.92
  5. Step 5: Solve for x
    x = 752,829.92/781.34
  6. Step 6: Final answer
    x = 963.51

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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.