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Finding the Fourth Proportional to 679.40, 1,019.10 and 405.80

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Solution

The fourth proportional to 679.40, 1,019.10 and 405.80 is: 608.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.40 : 1,019.10 = 405.80 : x
  2. Step 2: Convert to fraction form
    679.40/1,019.10 = 405.80/x
  3. Step 3: Cross multiply
    679.40x = 1,019.10 × 405.80
  4. Step 4: Simplify right side
    679.40x = 413,550.78
  5. Step 5: Solve for x
    x = 413,550.78/679.40
  6. Step 6: Final answer
    x = 608.70

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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.