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Finding the Fourth Proportional to 679.40, 1,017.79 and 405.71

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Solution

The fourth proportional to 679.40, 1,017.79 and 405.71 is: 607.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.40 : 1,017.79 = 405.71 : x
  2. Step 2: Convert to fraction form
    679.40/1,017.79 = 405.71/x
  3. Step 3: Cross multiply
    679.40x = 1,017.79 × 405.71
  4. Step 4: Simplify right side
    679.40x = 412,927.58
  5. Step 5: Solve for x
    x = 412,927.58/679.40
  6. Step 6: Final answer
    x = 607.78

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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.