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Finding the Fourth Proportional to 781.79, 1,171.85 and 319.37

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Solution

The fourth proportional to 781.79, 1,171.85 and 319.37 is: 478.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.79 : 1,171.85 = 319.37 : x
  2. Step 2: Convert to fraction form
    781.79/1,171.85 = 319.37/x
  3. Step 3: Cross multiply
    781.79x = 1,171.85 × 319.37
  4. Step 4: Simplify right side
    781.79x = 374,246.28
  5. Step 5: Solve for x
    x = 374,246.28/781.79
  6. Step 6: Final answer
    x = 478.71

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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.