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Finding the Fourth Proportional to 685.13, 945.30 and 390.29

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Solution

The fourth proportional to 685.13, 945.30 and 390.29 is: 538.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.13 : 945.30 = 390.29 : x
  2. Step 2: Convert to fraction form
    685.13/945.30 = 390.29/x
  3. Step 3: Cross multiply
    685.13x = 945.30 × 390.29
  4. Step 4: Simplify right side
    685.13x = 368,937.87
  5. Step 5: Solve for x
    x = 368,937.87/685.13
  6. Step 6: Final answer
    x = 538.50

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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.