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Finding the Fourth Proportional to 685.99, 946.42 and 391.15

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Solution

The fourth proportional to 685.99, 946.42 and 391.15 is: 539.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.99 : 946.42 = 391.15 : x
  2. Step 2: Convert to fraction form
    685.99/946.42 = 391.15/x
  3. Step 3: Cross multiply
    685.99x = 946.42 × 391.15
  4. Step 4: Simplify right side
    685.99x = 370,192.18
  5. Step 5: Solve for x
    x = 370,192.18/685.99
  6. Step 6: Final answer
    x = 539.65

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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.