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Finding the Fourth Proportional to 685.35, 945.39 and 390.57

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Solution

The fourth proportional to 685.35, 945.39 and 390.57 is: 538.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.35 : 945.39 = 390.57 : x
  2. Step 2: Convert to fraction form
    685.35/945.39 = 390.57/x
  3. Step 3: Cross multiply
    685.35x = 945.39 × 390.57
  4. Step 4: Simplify right side
    685.35x = 369,236.25
  5. Step 5: Solve for x
    x = 369,236.25/685.35
  6. Step 6: Final answer
    x = 538.76

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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.