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Finding the Fourth Proportional to 686.85, 947.72 and 520.80

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Solution

The fourth proportional to 686.85, 947.72 and 520.80 is: 718.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.85 : 947.72 = 520.80 : x
  2. Step 2: Convert to fraction form
    686.85/947.72 = 520.80/x
  3. Step 3: Cross multiply
    686.85x = 947.72 × 520.80
  4. Step 4: Simplify right side
    686.85x = 493,569.97
  5. Step 5: Solve for x
    x = 493,569.97/686.85
  6. Step 6: Final answer
    x = 718.60

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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.