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Finding the Fourth Proportional to 685.99, 946.64 and 391.20

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Solution

The fourth proportional to 685.99, 946.64 and 391.20 is: 539.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.99 : 946.64 = 391.20 : x
  2. Step 2: Convert to fraction form
    685.99/946.64 = 391.20/x
  3. Step 3: Cross multiply
    685.99x = 946.64 × 391.20
  4. Step 4: Simplify right side
    685.99x = 370,320.80
  5. Step 5: Solve for x
    x = 370,320.80/685.99
  6. Step 6: Final answer
    x = 539.84

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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.