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Finding the Fourth Proportional to 685.32, 945.68 and 390.54

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Solution

The fourth proportional to 685.32, 945.68 and 390.54 is: 538.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.32 : 945.68 = 390.54 : x
  2. Step 2: Convert to fraction form
    685.32/945.68 = 390.54/x
  3. Step 3: Cross multiply
    685.32x = 945.68 × 390.54
  4. Step 4: Simplify right side
    685.32x = 369,325.87
  5. Step 5: Solve for x
    x = 369,325.87/685.32
  6. Step 6: Final answer
    x = 538.91

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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.