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Finding the Fourth Proportional to 781.94, 1,079.20 and 487.31

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Solution

The fourth proportional to 781.94, 1,079.20 and 487.31 is: 672.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.94 : 1,079.20 = 487.31 : x
  2. Step 2: Convert to fraction form
    781.94/1,079.20 = 487.31/x
  3. Step 3: Cross multiply
    781.94x = 1,079.20 × 487.31
  4. Step 4: Simplify right side
    781.94x = 525,900.17
  5. Step 5: Solve for x
    x = 525,900.17/781.94
  6. Step 6: Final answer
    x = 672.56

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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.