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Finding the Fourth Proportional to 685.72, 946.24 and 391

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Solution

The fourth proportional to 685.72, 946.24 and 391 is: 539.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.72 : 946.24 = 391 : x
  2. Step 2: Convert to fraction form
    685.72/946.24 = 391/x
  3. Step 3: Cross multiply
    685.72x = 946.24 × 391
  4. Step 4: Simplify right side
    685.72x = 369,979.84
  5. Step 5: Solve for x
    x = 369,979.84/685.72
  6. Step 6: Final answer
    x = 539.55

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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.