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Finding the Fourth Proportional to 685.31, 945.55 and 405.42

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Solution

The fourth proportional to 685.31, 945.55 and 405.42 is: 559.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.31 : 945.55 = 405.42 : x
  2. Step 2: Convert to fraction form
    685.31/945.55 = 405.42/x
  3. Step 3: Cross multiply
    685.31x = 945.55 × 405.42
  4. Step 4: Simplify right side
    685.31x = 383,347.24
  5. Step 5: Solve for x
    x = 383,347.24/685.31
  6. Step 6: Final answer
    x = 559.38

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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.