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Finding the Fourth Proportional to 861.13, 1,289.12 and 842.60

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Solution

The fourth proportional to 861.13, 1,289.12 and 842.60 is: 1,261.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.13 : 1,289.12 = 842.60 : x
  2. Step 2: Convert to fraction form
    861.13/1,289.12 = 842.60/x
  3. Step 3: Cross multiply
    861.13x = 1,289.12 × 842.60
  4. Step 4: Simplify right side
    861.13x = 1,086,211.52
  5. Step 5: Solve for x
    x = 1,086,211.52/861.13
  6. Step 6: Final answer
    x = 1,261.38

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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.