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Finding the Fourth Proportional to 685.13, 945.36 and 390.35

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Solution

The fourth proportional to 685.13, 945.36 and 390.35 is: 538.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.13 : 945.36 = 390.35 : x
  2. Step 2: Convert to fraction form
    685.13/945.36 = 390.35/x
  3. Step 3: Cross multiply
    685.13x = 945.36 × 390.35
  4. Step 4: Simplify right side
    685.13x = 369,016.55
  5. Step 5: Solve for x
    x = 369,016.55/685.13
  6. Step 6: Final answer
    x = 538.61

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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.