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Finding the Fourth Proportional to 686.38, 947.23 and 391.64

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Solution

The fourth proportional to 686.38, 947.23 and 391.64 is: 540.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.38 : 947.23 = 391.64 : x
  2. Step 2: Convert to fraction form
    686.38/947.23 = 391.64/x
  3. Step 3: Cross multiply
    686.38x = 947.23 × 391.64
  4. Step 4: Simplify right side
    686.38x = 370,973.16
  5. Step 5: Solve for x
    x = 370,973.16/686.38
  6. Step 6: Final answer
    x = 540.48

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Half scale
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Double scale
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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.