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Finding the Fourth Proportional to 678.11, 1,016.70 and 431.49

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Solution

The fourth proportional to 678.11, 1,016.70 and 431.49 is: 646.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.11 : 1,016.70 = 431.49 : x
  2. Step 2: Convert to fraction form
    678.11/1,016.70 = 431.49/x
  3. Step 3: Cross multiply
    678.11x = 1,016.70 × 431.49
  4. Step 4: Simplify right side
    678.11x = 438,695.88
  5. Step 5: Solve for x
    x = 438,695.88/678.11
  6. Step 6: Final answer
    x = 646.94

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.