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Finding the Fourth Proportional to 686.96, 947.92 and 407.20

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Solution

The fourth proportional to 686.96, 947.92 and 407.20 is: 561.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.96 : 947.92 = 407.20 : x
  2. Step 2: Convert to fraction form
    686.96/947.92 = 407.20/x
  3. Step 3: Cross multiply
    686.96x = 947.92 × 407.20
  4. Step 4: Simplify right side
    686.96x = 385,993.02
  5. Step 5: Solve for x
    x = 385,993.02/686.96
  6. Step 6: Final answer
    x = 561.89

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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.