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Finding the Fourth Proportional to 686.20, 947.04 and 391.50

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Solution

The fourth proportional to 686.20, 947.04 and 391.50 is: 540.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.20 : 947.04 = 391.50 : x
  2. Step 2: Convert to fraction form
    686.20/947.04 = 391.50/x
  3. Step 3: Cross multiply
    686.20x = 947.04 × 391.50
  4. Step 4: Simplify right side
    686.20x = 370,766.16
  5. Step 5: Solve for x
    x = 370,766.16/686.20
  6. Step 6: Final answer
    x = 540.32

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1.5x scale

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.