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Finding the Fourth Proportional to 781.21, 1,077.56 and 515.57

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Solution

The fourth proportional to 781.21, 1,077.56 and 515.57 is: 711.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.21 : 1,077.56 = 515.57 : x
  2. Step 2: Convert to fraction form
    781.21/1,077.56 = 515.57/x
  3. Step 3: Cross multiply
    781.21x = 1,077.56 × 515.57
  4. Step 4: Simplify right side
    781.21x = 555,557.61
  5. Step 5: Solve for x
    x = 555,557.61/781.21
  6. Step 6: Final answer
    x = 711.15

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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.