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Finding the Fourth Proportional to 686.76, 947.79 and 407.09

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Solution

The fourth proportional to 686.76, 947.79 and 407.09 is: 561.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.76 : 947.79 = 407.09 : x
  2. Step 2: Convert to fraction form
    686.76/947.79 = 407.09/x
  3. Step 3: Cross multiply
    686.76x = 947.79 × 407.09
  4. Step 4: Simplify right side
    686.76x = 385,831.09
  5. Step 5: Solve for x
    x = 385,831.09/686.76
  6. Step 6: Final answer
    x = 561.81

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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.