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Finding the Fourth Proportional to 685.61, 946.21 and 390.94

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Solution

The fourth proportional to 685.61, 946.21 and 390.94 is: 539.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.61 : 946.21 = 390.94 : x
  2. Step 2: Convert to fraction form
    685.61/946.21 = 390.94/x
  3. Step 3: Cross multiply
    685.61x = 946.21 × 390.94
  4. Step 4: Simplify right side
    685.61x = 369,911.34
  5. Step 5: Solve for x
    x = 369,911.34/685.61
  6. Step 6: Final answer
    x = 539.54

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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.