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Finding the Fourth Proportional to 685.59, 946.12 and 390.85

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Solution

The fourth proportional to 685.59, 946.12 and 390.85 is: 539.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.59 : 946.12 = 390.85 : x
  2. Step 2: Convert to fraction form
    685.59/946.12 = 390.85/x
  3. Step 3: Cross multiply
    685.59x = 946.12 × 390.85
  4. Step 4: Simplify right side
    685.59x = 369,788.39
  5. Step 5: Solve for x
    x = 369,788.39/685.59
  6. Step 6: Final answer
    x = 539.38

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Half scale
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Double scale
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Similar ratio
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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.