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Finding the Fourth Proportional to 861.40, 1,187.40 and 529.20

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Solution

The fourth proportional to 861.40, 1,187.40 and 529.20 is: 729.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.40 : 1,187.40 = 529.20 : x
  2. Step 2: Convert to fraction form
    861.40/1,187.40 = 529.20/x
  3. Step 3: Cross multiply
    861.40x = 1,187.40 × 529.20
  4. Step 4: Simplify right side
    861.40x = 628,372.08
  5. Step 5: Solve for x
    x = 628,372.08/861.40
  6. Step 6: Final answer
    x = 729.48

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.