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Finding the Fourth Proportional to 685.78, 946.41 and 391.10

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Solution

The fourth proportional to 685.78, 946.41 and 391.10 is: 539.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.78 : 946.41 = 391.10 : x
  2. Step 2: Convert to fraction form
    685.78/946.41 = 391.10/x
  3. Step 3: Cross multiply
    685.78x = 946.41 × 391.10
  4. Step 4: Simplify right side
    685.78x = 370,143.32
  5. Step 5: Solve for x
    x = 370,143.32/685.78
  6. Step 6: Final answer
    x = 539.74

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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.