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Finding the Fourth Proportional to 678.42, 1,016.40 and 641.97

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Solution

The fourth proportional to 678.42, 1,016.40 and 641.97 is: 961.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.42 : 1,016.40 = 641.97 : x
  2. Step 2: Convert to fraction form
    678.42/1,016.40 = 641.97/x
  3. Step 3: Cross multiply
    678.42x = 1,016.40 × 641.97
  4. Step 4: Simplify right side
    678.42x = 652,493.23
  5. Step 5: Solve for x
    x = 652,493.23/678.42
  6. Step 6: Final answer
    x = 961.79

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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.