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Finding the Fourth Proportional to 685.61, 945.91 and 390.67

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Solution

The fourth proportional to 685.61, 945.91 and 390.67 is: 538.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.61 : 945.91 = 390.67 : x
  2. Step 2: Convert to fraction form
    685.61/945.91 = 390.67/x
  3. Step 3: Cross multiply
    685.61x = 945.91 × 390.67
  4. Step 4: Simplify right side
    685.61x = 369,538.66
  5. Step 5: Solve for x
    x = 369,538.66/685.61
  6. Step 6: Final answer
    x = 538.99

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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.