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Finding the Fourth Proportional to 686.90, 947.91 and 392.16

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Solution

The fourth proportional to 686.90, 947.91 and 392.16 is: 541.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.90 : 947.91 = 392.16 : x
  2. Step 2: Convert to fraction form
    686.90/947.91 = 392.16/x
  3. Step 3: Cross multiply
    686.90x = 947.91 × 392.16
  4. Step 4: Simplify right side
    686.90x = 371,735.63
  5. Step 5: Solve for x
    x = 371,735.63/686.90
  6. Step 6: Final answer
    x = 541.18

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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.