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Finding the Fourth Proportional to 685.37, 945.78 and 390.73

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Solution

The fourth proportional to 685.37, 945.78 and 390.73 is: 539.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.37 : 945.78 = 390.73 : x
  2. Step 2: Convert to fraction form
    685.37/945.78 = 390.73/x
  3. Step 3: Cross multiply
    685.37x = 945.78 × 390.73
  4. Step 4: Simplify right side
    685.37x = 369,544.62
  5. Step 5: Solve for x
    x = 369,544.62/685.37
  6. Step 6: Final answer
    x = 539.19

Related Problems

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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.