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Finding the Fourth Proportional to 686.72, 947.72 and 406.80

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Solution

The fourth proportional to 686.72, 947.72 and 406.80 is: 561.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.72 : 947.72 = 406.80 : x
  2. Step 2: Convert to fraction form
    686.72/947.72 = 406.80/x
  3. Step 3: Cross multiply
    686.72x = 947.72 × 406.80
  4. Step 4: Simplify right side
    686.72x = 385,530.46
  5. Step 5: Solve for x
    x = 385,530.46/686.72
  6. Step 6: Final answer
    x = 561.41

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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.