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Finding the Fourth Proportional to 685, 945.29 and 390.21

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Solution

The fourth proportional to 685, 945.29 and 390.21 is: 538.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    685 : 945.29 = 390.21 : x
  2. Step 2: Convert to fraction form
    685/945.29 = 390.21/x
  3. Step 3: Cross multiply
    685x = 945.29 × 390.21
  4. Step 4: Simplify right side
    685x = 368,861.61
  5. Step 5: Solve for x
    x = 368,861.61/685
  6. Step 6: Final answer
    x = 538.48

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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.