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Finding the Fourth Proportional to 685.65, 946.20 and 405.87

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Solution

The fourth proportional to 685.65, 946.20 and 405.87 is: 560.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.65 : 946.20 = 405.87 : x
  2. Step 2: Convert to fraction form
    685.65/946.20 = 405.87/x
  3. Step 3: Cross multiply
    685.65x = 946.20 × 405.87
  4. Step 4: Simplify right side
    685.65x = 384,034.19
  5. Step 5: Solve for x
    x = 384,034.19/685.65
  6. Step 6: Final answer
    x = 560.10

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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.