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Finding the Fourth Proportional to 861.36, 1,289.88 and 679.74

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Solution

The fourth proportional to 861.36, 1,289.88 and 679.74 is: 1,017.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.36 : 1,289.88 = 679.74 : x
  2. Step 2: Convert to fraction form
    861.36/1,289.88 = 679.74/x
  3. Step 3: Cross multiply
    861.36x = 1,289.88 × 679.74
  4. Step 4: Simplify right side
    861.36x = 876,783.03
  5. Step 5: Solve for x
    x = 876,783.03/861.36
  6. Step 6: Final answer
    x = 1,017.91

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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.