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Finding the Fourth Proportional to 781.56, 1,171.68 and 342.74

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Solution

The fourth proportional to 781.56, 1,171.68 and 342.74 is: 513.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.56 : 1,171.68 = 342.74 : x
  2. Step 2: Convert to fraction form
    781.56/1,171.68 = 342.74/x
  3. Step 3: Cross multiply
    781.56x = 1,171.68 × 342.74
  4. Step 4: Simplify right side
    781.56x = 401,575.74
  5. Step 5: Solve for x
    x = 401,575.74/781.56
  6. Step 6: Final answer
    x = 513.81

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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.