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Finding the Fourth Proportional to 685.50, 945.97 and 390.79

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Solution

The fourth proportional to 685.50, 945.97 and 390.79 is: 539.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.50 : 945.97 = 390.79 : x
  2. Step 2: Convert to fraction form
    685.50/945.97 = 390.79/x
  3. Step 3: Cross multiply
    685.50x = 945.97 × 390.79
  4. Step 4: Simplify right side
    685.50x = 369,675.62
  5. Step 5: Solve for x
    x = 369,675.62/685.50
  6. Step 6: Final answer
    x = 539.28

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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.