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Finding the Fourth Proportional to 685.45, 945.70 and 405.71

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Solution

The fourth proportional to 685.45, 945.70 and 405.71 is: 559.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.45 : 945.70 = 405.71 : x
  2. Step 2: Convert to fraction form
    685.45/945.70 = 405.71/x
  3. Step 3: Cross multiply
    685.45x = 945.70 × 405.71
  4. Step 4: Simplify right side
    685.45x = 383,679.95
  5. Step 5: Solve for x
    x = 383,679.95/685.45
  6. Step 6: Final answer
    x = 559.75

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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.